Term
| what are the names of the meninges that cover the brain and spinal cord? |
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Definition
Dura Mater (outermost layer)
- periosteal layer (attached to inner surface of skull)
- meningeal layer covering the brain
Arachnoid Mater (middle layer)
- separated from pia by the subarachnoid space (which is filled with CSF)
Subarachnoid space
Pia Mater (innermost layer) |
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Term
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Definition
| thickest, outermost layer of the meninges of the brain. Impermeable and protective. |
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Term
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Definition
Middle layer on the outside of the brain, found between the Pia Mater and the Dura Mater.
Impermeable. |
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Term
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Definition
| Rests on the brain surface and is the innermost layer of the meninges. Vascular membrane that adheres closely to the brain. Arteries carry sheath of Pia as enter parenhyma. Fuses with ependyma - choroid plexus. |
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Term
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Definition
From outside to inside:
Dura mater
Arachnoid mater
Subarachnoid space
Pia mater |
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Term
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Definition
| Filled with CSF. Found between the pia mater and the arachnoid mater. |
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Term
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Definition
| Large, low pressure blood vessel return path for cerebral venous blood |
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Term
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Definition
Structure that fits between the cerebellum and the occipital lobes.
Separates the posterior cranial fossa from the rest of the cranial vault. It arches upward along the median line to become continuous with Falx Cerebri to form Straight venous sinus.
**functions alongside the Falx Cerebri to restrict brain displacement associated with acceleration and deceleration. |
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Term
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Definition
Sickle shaped fold separating the cerebral hemispheres. The superior convex border of the Falx Cerebri forms the floor of the superior sagittal sinus.
The inferior border of the Falx Cerebri houses the inferior sagittal sinus. |
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Term
| Epidural hematoma location |
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Definition
Between the dura mater and the skull.
Cause: rupture of the middle meningeal artery during head trauma. |
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Term
| Subdural hemorrhage/hematoma |
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Definition
Location: either between the dura mater and arachnoid mater.
Usual cause:
Acute: rupturing of bridging veins that pass through en route to dural sinuses (shear injury).
Chronic: Also caused by atrophy in elderly people, where the brain pulls away from the dura mater and the skull itself. |
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Term
| Where do more brain aneurysms occur? |
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Definition
| Within the cerebral arteries, into the subarachnoid space. |
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Term
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Definition
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Term
| Where do all cerebral arteries and veins lie relative to the parenchyma? |
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Definition
| In the subarachnoid space |
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Term
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Definition
| Delicate threads that connect the pia mater and the arachnoid mater. |
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Term
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Definition
| Where the cerebral spinal fluid diffuses into the venous sinuses. |
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Term
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Definition
Brain has no pain receptors. Pain comes from the trigeminal and the first three cervical nerves innervating the meninges and vasculature.
Dura ABOVE the tentorium innervated by the trigeminal; forehead and face.
Dura BELOW the tentorium innervated by C1-3; back of the head and neck. |
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Term
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Definition
Space occupying lesions, raised intracranial pressure, irritation, stretching of the dura mater.
Tumor located above tentorium - front of head; below-back of head. |
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Term
| Migrane headaches depend on the activation of what? |
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Definition
| Depend on the activation of trigeminal afferents that densely innervate the meninges. |
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Term
| Where would you feel meningitis? |
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Definition
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Term
| Hangovers are due to a direct effect on what brain structure? |
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Definition
| On the meninges, tho it is multifactorial. |
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Term
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Definition
Occur in clusters (a few times a day) with spaces in between (a few days break in between).
"lancinating" or "boring" pain periorbital pain.
Known to be more painful than childbirth |
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Term
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Definition
| Released by afferent pain fibers. They dilate blood vessels in a recurring loop of excitation. (causing the pulsing feeling of headaches) |
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Term
| Blood supply to the brain |
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Definition
Can be divided into two divisions; posterior and anterior. Blood supply is also bi-lateral (both carotid arteries and vertebral arteries are separated into right and left)
Posterior: subclavian artery goes through the vertebra through the vertebral artery, then the basilar artery to the brain.
Anterior: coming off the common carotid artery is the external and internal carotid arteries. |
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Term
| What is the circle of willis? |
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Definition
An anastamosis --> a rounding or joining of vessels that allows for bypassing of vascular blockages without compromises.
Vertebral artery --> basilar artery --> posterior communicating artery --> anterior communicating artery |
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Term
| Describe posterior brain circulation |
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Definition
| Aorta --> right/left subclavian artery --> extracranial / intracranial artery --> basilar artery --> posterior cerebral arteries |
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Term
| Describe anterior brain circulation |
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Definition
| Aorta -->right/left common carotid artery --> external/internal carotid artery --> Anterior cerebral artery / middle cerebral artery |
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Term
| Which artery of the brain supplies for the largest areas of the brain? |
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Definition
| The middle cerebral artery |
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Term
| Which artery is most commonly the culprit in a stroke? |
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Definition
| The middle cerebral artery. It covers so much of the brain that it is most commonly the culprit of such damage. |
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Term
| Cortical areas of the brain are supplied by what arteries? |
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Definition
| By the anterior cerebral artery, the posterior cerebral artery and the medial cerebral artery. |
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Term
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Definition
| Supplies most of the cortices and comes off the internal carotid artery at a deep aspect of the brain. Has an artery stem that has many little feeders coming off of it, leading to the aspects of the brain. |
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Term
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Definition
Caused by damage to the right hemisphere middle cerebral artery.
Patients experience an unawareness of the patients own body contralateral to the lesion. Patients may seem unaware or deny their handicap. |
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Term
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Definition
Caused by damage to the right hemisphere middle cerebral artery.
Patients may experience unawareness of quite dramatic impairments, such as blindness or paralysis. |
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Term
| Contralateral hemiparesis |
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Definition
| Involve mainly the face and arm; precentral and postcentral gyri. |
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Term
| Damage to the left hemisphere middle cerebral artery |
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Definition
Can damage Broca's/Wernicke's area's.
Can cause aphasias --> cause difficulty with language. |
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Term
| Parietal neglect syndrome |
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Definition
Characterized by a failure to recognize side of body contralateral to injury.
May not bathe contralateral side of body or face
Denying own limbs
Objects in contralateral visual field may be completely ignored. |
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Term
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Definition
| The disturbance in formulation or comprehension of understanding. Damage occurs on left side of the brain. |
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Term
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Definition
Difficulty producing speech though comprehension is intact.
Disordered grammar and syntax, with meaningful produced with great effort.
Damage in Broca's area. |
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Term
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Definition
Difficulty comprehending speech.
Speech is fluent, well structured, grammar and syntax are adequate but nonsensical.
Damage in wernickes area |
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Term
| Contralateral hemiparesis |
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Definition
Caused by damage to the anterior cerebral artery.
Characterized by paralysis or weakness on one side of the body. Hemisensory loss involving mainly the leg and foot (paracentral lobule).
*personality changes could occur as well. |
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Term
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Definition
Occurs through damage to the posterior cerebral artery.
Loss of vision of one half of the visual field. |
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Term
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Definition
Occurs through damage to the posterior cerebral artery.
Inability to recognize or interpret objects in the visual field. |
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Term
| Memory impairment could mean that there is damage to what part of the brain? |
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Definition
| Damage to the posterior cerebral artery could cause memory impairment. |
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Term
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Definition
Damage to the inferior temporal cortex. Most commonly caused by a posterior carotid artery stroke.
Characterized by an inability to identify facial characteristics - may not be able to recognize faces at all.
Aware that some sort of visual stimulus is present and can discriminate subtle shape differences, even able to recognize the age, sex, and 'likeability' of a face.
Therefore people are identified through other characteristics. |
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Term
| Intraparenchymal hemorrhage |
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Definition
| Bleeding occurring within the brain. |
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Term
| Extraparenchymal hemorrhage |
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Definition
| Bleeding occurring at the surface of the brain (subarachnoid) |
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Term
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Definition
| Accumulation of blood that clots |
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Term
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Definition
| Material (blood clot, air, fat) carried from one point to lodge in another |
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Term
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Definition
| Embolus becomes lodged in an artery and obstructs flow |
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Term
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Definition
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Term
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Definition
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Term
| Venous drainage of the cerebral hemisphere |
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Definition
Superficial veins drain into superior sagittal sinus and the cavernous sinus.
Deep veins drain into the deep venous conduits
Superior sagittal sinus drain into two transverse sinuses, heading out the sigmoidal sinus, down the internal jugular and then out. |
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Term
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Definition
| When a portion of the brain is being utilized, there is increase bloodflow to that region. This can be shown using modern imaging techniques |
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Term
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Definition
"Blood Oxygen Level Dependent Signal"
This is what fMRI's are based off of.
Exploits paramagnetic nature of oxygenated hemoglobin. Oxygenated blood, conversely, is NOT magnetic.
The bold signal is affected by changes in ratio between deoxygenated and oxygenated blood. |
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Term
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Definition
Type of glial cell that outnumbers neurons by 10x.
Cause vasoconstriction of an arteriole. Work by signalling calcium signals and spreading this information as a wave. |
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Term
| Where is the ventricular system found |
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Definition
| Sits deep within the brain. It lies within the core of the forebrain and brainstem. |
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Term
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Definition
Functions:
- Cushions/protects CNS from trauma.
- Provides mechanical buoyancy and support for the brain
- Serves as lymphatic system for the brain
- Important for maintaining constant external environment for neurons and glia
Located:
- In the ventricles, subarachnoid space around the brain and spinal cord
Components:
- 99% water, proteins, glucose, Na+, K+, H+/HCO_3, Ca+2, Mg+2, No RBC and very little WBC. |
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Term
| Where is cerebral spinal fluid formed |
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Definition
| Lateral, third and fourth ventricles by the choroid plexuses. |
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Term
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Definition
Vascular-like structure derived from the pia, covered with fenestrated cuboidal epithelium of the ependyma. located around the lateral, third and fourth ventricles.
The cuboidal epithelium set up an osmotic gradient created by the active transport of solutes, exploiting this to diffuse fluid across. |
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Term
| Describe the structures that the cerebral spinal fluid moves through when it's being produced from the lateral ventricles. |
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Definition
1) Lateral ventricles
2) Intraventricular foramina of Monro
3) Third Ventricle
4) Cerebral aqueduct of Sylvius
5) Fourth Ventricle
6) Foramina of Magendie and Luschka
7) Subarachnoid space, central canal of spinal cord, over spinal cord, over convexity of brain
8) Reabsorbed by arachnoid granulations |
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Term
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Definition
| Structures that poke up through the meningeal layer into the dural venous sinuses. They are the structures that reabsorbs used cerebral spinal fluid, working as a sort of one-way pressure sensitive valve. (when CSF Pressure > venous pressure, it empties out of the arachnoid granulation) into the superior sagittal sinus. |
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Term
| Cerebral spinal fluid reabsorption |
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Definition
| Cerebral spinal fluid is reabsorbed by the dural venous sinuses (particularely the superior sagittal sinus) through arachnoid granulations. |
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Term
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Definition
Optic swelling that is secondary (a sign of) to elevated intercranial pressure.
Edema in area of optic disc caused by compression of retinal vein as it crosses the extension of the subarachnoid space to enter the optic nerve and stasis of axoplasmic flow |
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Term
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Definition
An abnormal increase in the amount of cerebrospinal fluid within the ventricles of the brain. Before the sutures of the skull fuse, the head becomes enlarged (infants).
Causes an obstruction in CSF circulation (aqueductal stenosis)
Exit foramina from the ventricular system not formed. CSF cannot escape subarachnoid space.
Generalized ventricular enlargement occurs with obstruction at or below the cerebral aquaduct.
Treated using a ventriculoperitoneal shunt treatment to divert excess CSF from ventricles to abdominal cavity. |
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Term
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Definition
| Arnold Chiari phenomenon is related to hydrocephalus, where there is displacement of the hindbrain downward through the foramen magnum to obstruct cerebral spinal fluid flow. |
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Term
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Definition
| Large hole where your brainstem is. Flow being obstructed there can cause many problems as well. |
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Term
| How can the cerebral spinal fluid be affected by disease states? |
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Definition
Can become grossly bloody or yellow from blood pigments. Protein content can be left behind after hemorrhage (subarachnoid).
Change in vascular permeability or bilirubin brought from plasma to cerebral spinal fluid.
Cloudiness is a sign of many leukocytes caused by meningitis or encephalitis. |
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Term
| Entry of cerebral spinal fluid to the bathing the brain |
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Definition
Leaves through the foramen and circulates the brain.
There are large gaps in the pia matter which allows for the exit of the cerebral spinal fluid from the ventricles. |
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Term
Which of the following is fenestrated:
a) Dura mater
b) Pia mater
c) Arachnoid mater
d) None of the above |
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Definition
The answer is B
The pia mater is fenestrated. |
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Term
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Definition
Diffusion barrier that impedes influx of most compounds from blood to brain.
Absolutely essential for maintaining a constant internal environment.
Is a key obstacle in the delivering of drugs to the brain. They overcome this by manipulating the transport mechanisms. |
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Term
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Definition
Controls individual functions mediated by the activity of smooth muscle fibers, cardiac muscle fibers and glands in order to maintain homeostasis.
Comprised of two major systems:
Sympathetic
- Fight or flight
Parasympathetic
- Resting state |
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Term
| Which division of the nervous system primarily releases adrenaline? |
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Definition
| The sympathetic nervous system |
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Term
| Which division of the nervous system primarily releases acetylcholine? |
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Definition
| The parasympathetic division of the nervous system |
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Term
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Definition
Regions of the central nervous system rich in neuronal cell bodies and neuropil.
*in the neuropil is where everything synapses: dendrites and presynaptic terminals meet and synapse there. |
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Term
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Definition
| Refers to large axon tracts in the brain and spinal cord. Most of the axons are myelinated. |
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Term
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Definition
| White matter fiber that connects corresponding regions of the two hemispheres. |
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Term
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Definition
| White matter fiber that connects various cortical regions within the same hemisphere. |
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Term
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Definition
| White matter fiber that connects afferent and efferent nerve fibers passing to and from the brain stem to the entire cortex. |
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Term
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Definition
| 1. The corpus callosum is a thick band of nerve fibers that divides the cerebrum into left and right hemispheres |
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Term
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Definition
Area for initiating speech.
Therefore damage to it results in:
- Difficulty with producing speech
- Comprehension, however, remains intact |
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Term
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Definition
Area for comprehending speech.
Therefore damage to it will result in:
- Difficulty comprehending speech
- Speech will remain, however, fluent and well structured. |
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Term
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Definition
| Neural pathway connecting Broca's area to Wernicke's area involved in the generation and understanding of language. |
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Term
| How many regions are there in the cortex? How do this regions differ? |
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Definition
The laminar regions of the cortex are broken up into six regions.
The different neurons in the different layers carry out different functions. |
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Term
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Definition
| When one neuron synapses onto many neurons |
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Term
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Definition
| When several neurons come in and synapse onto one neuron. |
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Term
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Definition
| Type of afferent control wherein the stimulation of afferent motor neurons innervates collateral inhibitory interneurons in the spine - inhibiting the afferent neurons of the antagonist muscles. |
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Term
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Definition
| Type of self-regulation. When one neuron fires onto another neuron at a high enough frequency, the second neuron will fire collaterally and stimulate an inhibitory interneuron which feedsback onto that same neuron (inhibiting its effects) |
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Term
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Definition
| Protein found in the venom of black widow spiders that causes the massive exocytosis of synaptic vesicles containing neurotransmitters. |
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Term
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Definition
| Neurotoxin that blocks Ach receptors, causing paralysis. |
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Term
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Definition
| Causes paralysis in its victims by blocking ACh receptors |
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Term
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Definition
| Toxin that comes from marine cone snails. They shoot venomous darts into its prey. Blocks calcium, acetylcholine, glutamate and sodium channels. |
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Term
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Definition
| Type of ion channel that acts as a cold sensor. |
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Term
| Neuromodulator systems that have widespread diffuse projections: |
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Definition
| Acetylcholine, dopamine, norepinephrine, serotonin. |
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Term
| ACh brain neuromodulator system originate. Functions. Effects of blocking. |
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Definition
Brainstem and basal forebrain.
Generally excitatory and are thought to function in attention, memory and learning.
Blocking of ACh causes delerium and memory deficit.
*the basal forebrain is damaged in Alzheimer's disease. |
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Term
| Dopamine brain neuromodulator system originate. Functions. Effects of blocking. |
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Definition
Substantia nigra and ventral tegmental area.
Wide ranged functions (cognition, pain, voluntary movement, motivation, mood, attention)
Mesostiatal - damaged in parkinsons disease
Mesolimbic - involved in the positive symptoms of schizophrenia such as hallucinations.
Mesocortical - involved in cognitive deficits and 'negative' symptoms of schizophrenia. |
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Term
| Norepinephrine brain neuromodulator system originate. Functions. Effects of blocking. |
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Definition
Locus coeruleus and lateral tegmental area. Projects into entire forebrain.
Functions in attention, sleep-wake cycles, mood and sympathetic activities.
NE and 5HT are important in mood disorders such as depression and manic-depressive disorder. In anxiety disorders, including OCD. |
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Term
| Serotonin brain neuromodulator system originate. Functions. Effects of blocking. |
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Definition
Rape nuclei; rostral raphe projects to entire forebrain; caudal raphe projects to cerebellum, medulla, and spinal cord.
Involved in depression, anxiety, OCD, aggressive behavior & some eating disorders.
The caudal raphe functions in pain modulation. |
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Term
| Astrocyte types, functions. |
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Definition
Star shaped glial cells that hold neurons in place, getting nutrients to them and digesting parts of dead neurons.
Cannot generate action potential.
However communicate with neurons and modify the signals they send/receive.
Types: established, probable, emerging. |
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Term
| Established astrocyte normal and pathological functions. |
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Definition
Normal functions:
Sequestration/redistribution of K+ during neural activity.
Removal of glutamate and GABA at synapses
Synthesis of precursor for glutamate and GABA production.
Pathological functions:
Alexander disease
Cytotoxic brain edema
Glioma formation
Failure at extracellular glutamate homeostasis |
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Term
| Probable astrocyte normal and pathological functions. |
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Definition
Normal functions:
Providing energy substrate to neurons
Sharing energy substrate derived from glycogen with neurons
Brain water homeostasis
Influencing integrity of blood-brain barrier
Regulation of extracellular pH
Pathological:
Hepatic encaphalopathy
Modulation of stroke outcome |
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Term
| Emerging astrocyte normal functions |
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Definition
Normal functions:
Modulation of excitatory / inhibitory synapses
Regulation of synaptogenesis
Regulation of neurogenesis in adult brain
Detoxification of brain free radical species |
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Term
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Definition
Mobile, immune competent cells of the central nervous system.
*when they sense trauma, they send out processes all around them in order to commune info about that trauma
*thought to contain or minimize damage of lesions (reducing small ones)
*known to be involved in mostly pathological condition (MS) |
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Term
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Definition
| Found in the central nervous system. Wrap around the axons of the neuron with myelin which results in an increased conduction velocity. |
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Term
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Definition
| Line the cavities of the brain and central canal of the spinal cord. Involved in the production and secretion of the cerebral spinal fluid. |
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Term
| Olfactory system - mechanism/function |
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Definition
| Odor molecules in mucous are grabbed by cilia, binding to a protein and initiates a transduction process. In this case The g-protein called G_olf is activated and activates the production of cAMP. The increased production of cAMP causes cAMP channels to open. Ions move in and cause depolarization. Typically chloride leaves - closing of these channels causes membrane depolarization. |
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Term
| How are smells differentiated? |
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Definition
1) There are different types of odorant receptors - each receptor cell has a single receptor protein expressed for a "preferred" odor.
1. Each receptor cell is broadly tuned - allows for binding of different odors more or less readily --
2. Brain distinguishes individual odors by looking at the combination of responses.
2) Different odors will elicit different patterns of action potential firing. (different glomerular activity)
1. Temporal and spatial coding |
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Term
| Olfactory signal transduction pathway |
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Definition
Olfactory sensory neurons --> olfactory bulb (@ glomerulus, synapses onto 2nd order olfactory neurons) --> olfactory tract --> brain
The second-order olfactory neurons are found in the olfactory bulb. |
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Term
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Definition
Contain microcells… Processes the information from olfactory sensory neurons synapsing on the microcells of the glomeruli (synaptic part of the glomerulus).
**there is glomerulus convergence: this means that each glomerulus receives input from only receptor cells of one type. This means that there may be a map of odorant processing (zone-to-zone projection) |
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Term
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Definition
Secondary neurons that take information and do something with it.
Glomerulus, involving the olfactory system, have microcells. |
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Term
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Definition
Refers to the fact that similar odorant receptors tend to be localized in the same zone of the olfactory bulb. Different odors elicit different patterns of glomerular activation.
Activation is, therefore, very selective and the smell of an odor is translated into a specific map in the neural space.
**there's a spatial code in which information is conveyed by the relative positions of the activated neurons.
-------------------------------------
the receptors are homologous and concentrated in certain areas (zones). When they do this they project very orderly to the olfactory bulb. So the map that there is there gets mapped to the higher centers in 1:1 mapping. |
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Term
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Definition
A code in which information is conveyed by the relative positions of activated neurons.
Example: different odors elicit different patterns of glomerular activation |
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Term
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Definition
| A code in which information is carried by the relative timing of action potentials in a population of neurons |
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Term
| Describe the layers of cells that odorant sensation transduce through. |
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Definition
Mucus layer (olfactory neurons)--> primary neurons take information back to the glomerular layer. --> there they synapse onto the secondary neurons (the mitral cells) that take the information to higher centers to do something with it.
Zonal mapping occurs at the level of the glomerulus. |
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Term
| How are mitral cells coded for different odorant types? |
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Definition
Mitral cells specify by the shape of the chemical molecule.
Also can be specific by para/meta/ortho structures |
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Term
| Lateral inhibition - contrast |
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Definition
| Lateral inhibition can be used to contrast sensory inputs. A high amount of stimulation at one point will cause the firing of interneurons at that point, which will cause an inhibition on the neurons that are located nearby - causing them to fire at a reduced rate. |
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Term
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Definition
A type of inhibitory interneuron involved in olfactory transduction.
May enhance the contrast between strongly activated and faintly activated glomeruli. |
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Term
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Definition
| The inability to perceive odors |
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Term
| How is olfactory sense affected by age? |
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Definition
| There is a decrease in olfactory ability with age - both at the levels of the receptors and at the level of activity in the olfactory regions of the brain. |
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Term
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Definition
Specifies-specific odorants for communication - compounds that, at concentrations below the level of consciousness, can elicit both behavioral responses and different patterns of brain activation in adult female and male human subjects.
Example: women and their menstrual cycles |
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Term
| Describe the cells located at the retina |
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Definition
| Photoreceptor cells, bipolar cells, horizontal cells, ganglion cells |
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Term
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Definition
| Region located at the back of the eye where the neurons leave the eye. There are no photoreceptors located there. |
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Term
| Nasal retina/temporal retina |
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Definition
Nasal retina - located nearest to the noise
Temporal retina - located near the temple. |
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Term
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Definition
Area of retina specialized for high visual acuity in the center of the macula; contains high density of cones.
Foveola = avascular zone where light is not refracted, but instead hits the photoreceptors directly. |
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Term
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Definition
| Responsible for our ability to see color - contains one of three different photopigments. |
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Term
| Photoreceptor cell structure |
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Definition
Outsegment - where actual photo-transduction occurs
Inner segment - experiences the depolarization process
Synaptic terminals - where synaptic release occurs |
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Term
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Definition
| Malformation or malfunctioning of color-specific cones |
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Term
| Regional differences in retinal structure |
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Definition
Peripheral: low light sensitivity
- Much higher ratio rods to cones
- Higher ratio of photoreceptors to ganglion cells
â—‹ Making it so that the peripheral retina are much more sensitive to low light levels.
Central: high resolution vision
- Cones only
- Low ratio of photoreceptors to ganglion cells |
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Term
| What gives good visual acuity? |
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Definition
The fovea -- there is a little divot within the fovea that is avascular.
Since there is no vasculature that the light must refract through to reach the photoreceptive cells, there is no blurring of the image. |
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Term
| Intrinsically photoreceptive retinal ganglion cells (ipRGC's) |
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Definition
| Cells that contain photopigment, melanopsin, and can also encode and transmit information about light directly. |
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Term
| Phototransduction mechanism |
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Definition
Rhodopsin (complex protein containing opsin + retinal molecule) - when light hits it, retinal undergoes conformational change, activating g-protein Transducin, activating enzyme phosphodiesterase which cleaves the cGMP floating around into GMP. This results in a closing of sodium channels and reduced action potentials.
**causes massive hyperpolarization when light hits. |
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Term
| This neurotransmitter is released constantly in the eye when you are in the dark. |
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Definition
| Glutamate is constantly released in the dark. This stimulates the formation of cGMP which causes Na channels to be open. |
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Term
| In retinal processing, which cell is the one that fires action potentials |
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Definition
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Term
| Retinal processing pathway |
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Definition
Photoreceptor --> bipolar cell --> ganglion cell
**also interacts with horizontal and amacrine cells which release GABA, an inhibitory neurotransmitter - causing lateral inhibition. |
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Term
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Definition
On/off bipolar cells.
On bipolar cells:
Have g-protein coupled receptors (mGluR6).
Hyperpolarize in response glutamate released by photoreceptors.
Off bipolar cells:
Glutamate gated ion channels (AMPA; kainate)
Depolarize to the release of glut from photoreceptor
Influenced positively all the time in the dark
On bipolar cells => inhibited by glutamate
Off bipolar cells ==> activated by glutamate |
|
|
Term
| How does light affect on/off bipolar cells |
|
Definition
On bipolar cells - depolarized by light
Off bipolar cells - hyperpolarized when lights are on |
|
|
Term
| Bipolar cell receptive fields |
|
Definition
Receptive field: area of the retina that, when stimulated with light, changes the cell's membrane potential
Receptive field center:
Circular area of retina providing direct photoreceptor input bipolar cell
Receptive field surround:
Surrounding area of retina providing indirect photoreceptor input to bipolar cell via horizontal cells |
|
|
Term
| What do on/off center bipolar cells synapse onto and with what neurotransmitter. |
|
Definition
On center bipolar cells synapse onto on-center ganglion cells
Off center bipolar cells synapse onto off center ganglion cells.
Neurotransmitter: glutamate |
|
|
Term
| How are on/off center ganglion stimulated or inhibited by on/off center bipolar cells |
|
Definition
Light:
Photoreceptor cells are hyperpolarized
On-center bipolar cells are depolarized - off centers hyperoplarized.
On-center ganglion cells fire AP's
Off center ganglion cells stop firing AP's
No light:
Photoreceptor cell depolarizes
On-center bipolar cells hyperpolarize - off centers depolarize
On-center ganglion cells stop firing AP's
Off center ganglion cells fire AP's |
|
|
Term
| What are optical ganglion cells sensitive to what? |
|
Definition
Are particularly sensitive to differences in illumination that occur within their receptive fields and not to changes in illumination that include both receptive field center and the receptive field surround.
Response to stimulation of the center is canceled by the response to stimulation of the surround. |
|
|
Term
|
Definition
Type of ganglion cell. Important for high spatial resolution vision - detailed analysis of shape, size and color of objects.
90% of ganglion population type.
Small receptive field.
Slow axon conduction velocities
Sustained firing to presence of visual stimuli
Can transmit info about color |
|
|
Term
|
Definition
Type of ganglion cell. Important for high temporal resolution - such as evaluating the location, speed and direction of a rapidly moving object.
5% of ganglion population type.
Transient burst of AP's to the presentation of visual stimuli.
Fast conduction
Sensitive to low contrast stimulus
Cannot transmit info about color |
|
|
Term
| The retinofugal projection |
|
Definition
Optic nerve
Optic chiasm
Optic tract |
|
|
Term
| Where are the monocular parts of the visual field? |
|
Definition
At the far left and far right of the visual field.
There is overlap at the center of the visual field. |
|
|
Term
| How does light hit your fovea? |
|
Definition
The light hits your fovea in such a way that the image is inverted and upside down.
The higher centers of the brain then process and flip the image again. |
|
|
Term
| Where does the right visual field hit relative to the retina |
|
Definition
| Hits the nasal retina of the right eye and the temporal retina of the left eye. |
|
|
Term
| Where does the left visual field hit relative to the retina |
|
Definition
| Hits the nasal retina of the left eye and the temporal retina of the right eye. |
|
|
Term
| How do the fibers cross when light comes in from the right visual field. |
|
Definition
Coming from the right visual field, light hits the right temporal retina and he left nasal retina.
The left nasal retina crosses over to the right optic tract, the right temporal retina goes down the right optic tract. |
|
|
Term
| How do the fibers cross when light comes in from the left visual field. |
|
Definition
Coming from the left visual field, light would hit the left temporal retina and the right nasal retina.
The left temporal retina continues down the left optic tract, the right nasal retina crosses the optic chiasm to continue down the left optic tract. |
|
|
Term
| Retinal ganglion cell targets |
|
Definition
*terminates in several different areas*
Hypothalamic region - regulation of circadian rhythms. Melanin and melanopsin photoreceptors are involved in those processes.
Pretectal (pretectum) area - reflex control of pupil and lens. (pupils dilate when it's dark and contract when it's light)
Colliculus - controlled by brainstem regions of the brain, governing reflexive eye movements of the eye-ball.
Striate cortex - located in the posterior cortical regions - this is where processing and understanding of visual scenes occurs. |
|
|
Term
|
Definition
Unconsciously controlled reaction to a stimuli.
Example:
Antagonistic contraction of muscles due to interneuron-involved reflex. (where interneurons connect afferent somatosensory fibers to efferent somatic fibers of antagonistic muscles within the spinal cord). |
|
|
Term
| The pupillary light-reflex pathway -- starting in left eye |
|
Definition
Shine in the left eye
Information taken down the optic nerve, but not to higher processing centers.
It instead terminates in the pretectal region
It then bifurcates after the pretectal region and sends out further afferent inputs to the edinger-westphal nucleus.
From there, it is efferent motor neurons going bilaterally out the preganglionic parasympathetic (ocular motor nerve) nerve.
The preganglionic parasympathetic nerve will synapse through ciliary ganglion, leading to post ganglionic terminations at the iris muscles
The iris muscles control and cause the pupils to constrict. |
|
|
Term
| The direct response (ocular) |
|
Definition
Where an eye is stimulated by a light and contracts.
There is a phenomenon called the consensual response by the other eye in a normal situation. |
|
|
Term
| Consensual response (ocular) |
|
Definition
| Where one eye is directly stimulated, but the other eye responds in kind to this stimulation. |
|
|
Term
| What does it mean if a physician shines a light in the left eye and it constricts but the consensual response does not occur. What does this indicate there is an issue with? |
|
Definition
| It indicates that there may be an issue with the visceral motor outflow, so something is damaged in either the edinger-westphal nucleus or the ocular motor nerve. |
|
|
Term
| What does it mean if a physician shines a light in the eyes of a patient but elicits no response in either eye. |
|
Definition
| You are not getting afferent information back to the higher centers -- there's a problem with the optic nerves. |
|
|
Term
| What does it mean if you shine light in one eye and get no response, but shine light in the other eye and get both consensual and direct responses. |
|
Definition
| Suggests damage to the sensory input of that eye, possibly to the retina or optic nerve. |
|
|
Term
| Central projections of retinal ganglion cells - what is the pathway? |
|
Definition
Stimulation of eyes -->
Optic tract -->
Lateral geniculate nucleus of the thalamus -->
Optic radiation -->
Primary visual cortex (striate cortex) |
|
|
Term
| What happens if the striated visual cortex is damaged. True or false: the person will be blind. |
|
Definition
| "blindsight" occurs due to this. The person is technically blind, but could direct themselves through an obstacle course - but the individual lacks visual awareness. |
|
|
Term
|
Definition
To make sense of what we're seeing and just saw - all the features about how it looks and how fast its moving.
If it were damaged, you couldn't see, but you would still be seeing. The individual lacks visual awareness. |
|
|
Term
|
Definition
Structure of the retinal-ganglion pathway.
It is involved with more reflexive things. Seems to be primarily involved with where things are located. |
|
|
Term
|
Definition
Caused by damage to the V1 area of the cortex (the visual area).
Blindsight is due to the preservation of the extrastriate pathways that bypass the visual cortex.
However the extrastriate areas are not able to support visual awareness. |
|
|
Term
| Lateral Geniculate Nucleus - cell types. Organization. |
|
Definition
Contains 6 major cell layers
- Two ventral magnocellular layers
â—‹ m-type retinal cells found exclusively here
- Four dorsal parvocellular layers
â—‹ p-type retinal cells found exclusively here
â—‹ They receive input from both eyes, from the contralateral field. (nasal retina of one eye and temporal retina of the other)
Each layer receives projections from either the ipsilateral or contralateral retina. Individual geniculate neurons are monocular - driven by either the left or right eye but not both.
-->
Magnocellular:
Contralateral
Ipsilateral
Parvocellular:
Ipsilateral
Contralateral
Ipsilateral
Contralateral
--> |
|
|
Term
| The right visual field will go to which lateral geniculate nucleus? |
|
Definition
| The right visual field will go to the left lateral geniculate nucleus. |
|
|
Term
| Where, relative to the calcarine sulcus, is the upper visual field mapped? |
|
Definition
The upper visual field is mapped below the calcarine sulcus.
The lower visual field is mapped above the calcarine sulcus. |
|
|
Term
|
Definition
Region of the brain, above which there is the region for the termination of the lower visual field.
Below which there is the termination for the upper visual field. |
|
|
Term
|
Definition
| Small blind spots in the visual field |
|
|
Term
|
Definition
| Large visual field deficits --- large blind spots. |
|
|
Term
| If you were to cut the connection at the optic chiasm, what part of the visual field would not be percieved by the upper processing centers? |
|
Definition
If you were to cut at the optic chiasm, then the information from the nasal retina will not be delivered to the upper processing areas.
However, the information from the temporal retinal regions will be. |
|
|
Term
| Of the layers of the visual cortex, in which do the greatest number of neurons synapse? |
|
Definition
In layer #4.
Magnocellular lateral geniculate |
|
|
Term
| Where do magnocellular lateral geniculate neurons synapse? |
|
Definition
|
|
Term
| Where do parvocellular lateral geniculate neurons synapse? |
|
Definition
|
|
Term
|
Definition
Refers to regions of neurons with similar ocular preference - either right or left eye.
There is a level of domination in the IV layer of the cortical region of the visual cortex. |
|
|
Term
| Location where the mixing of visual pathways occurs from both eyes |
|
Definition
The striate cortex.
This is where the mixing of neurons begins! This creates binocular input.
At the geniculate lateral nucleus, before this, the neurons have a form of retinotropic map. |
|
|
Term
| What is the first step of processing conscious visual awareness. |
|
Definition
| The mixing of neurons at the level of the striate cortex. |
|
|
Term
|
Definition
Signals from the two eyes are combined at the cellular level in the striate cortex.
*provides the basis for the sensation of depth (stereopsis) |
|
|
Term
|
Definition
|
|
Term
|
Definition
Disparity between the two eyes views of objects nearer or farther than the fixation point is interpreted as depth.
(information hits slightly different parts of the retina) |
|
|
Term
|
Definition
| Retinal cell type that respond to stimuli and discharge to stimulation/disparities beyond the plane of fixation. |
|
|
Term
|
Definition
| Retinal cell type that respond to stimuli at disparities in front of the plane of fixation. |
|
|
Term
| Orientation-selective neurons |
|
Definition
| The basis of how we interpret movement in our environment. There are specific neurons that are being processed in certain orientation (light/dark bars that are angled at certain orientations cause specific orientation of neurons to fire). |
|
|
Term
| Cortical neurons responding to optical stimulation are sensitive to what features of stimuli |
|
Definition
Some neurons are specifically tunes to the orientation of light/dark contrasting bars
Some neurons are specifically tuned to the length of visual stimulus. **they decrease their firing rate of response when the bar exceeds a specific length.
Some neurons are specific to the direction in which an edge moved across their receptive field.
Therefore: there are
Length selective neurons
Orientation selective neurons
Direction selective neurons |
|
|
Term
| Orientation specific neurons are thought to be specialized for what function? |
|
Definition
| For the analysis of shape. |
|
|
Term
| Invarient neural representation |
|
Definition
| Different views of the same person or object evoke identical activity patterns in the striated cortex |
|
|
Term
| Variant neural representation |
|
Definition
| Different views of the same person or objet evoke different activity patterns in the striated cortex. |
|
|
Term
| How do neurons encode visual perception? |
|
Definition
1) A broad and distributed population of neurons are relied on for schemes of representation. ***
2) Schemes based on the idea that the brain has a separate neuron to detect and represent every object. "grandmother neurons" |
|
|
Term
|
Definition
Pressure waves generated by vibrating air molecules.
Sound pushes (compressing air) and pulling the air (rarefied air) |
|
|
Term
|
Definition
|
|
Term
| Loudness is measured in what units |
|
Definition
|
|
Term
| Pitch is measured in what units |
|
Definition
| Frequency or cycles/second (Hz) -- Hertz |
|
|
Term
| What is the frequency range in which people can perceive sound? |
|
Definition
|
|
Term
|
Definition
Most sounds consist of complex wave forms.
The inner ear acts like an acoustical prism -- it decomposes the complex waveform into components and myriad of constituent tones. |
|
|
Term
| The different parts of the ear |
|
Definition
Outer ear
Middle ear --> tympanic membrane, ossicles (stapes, incus and malleus)
Inner ear --> |
|
|
Term
| Function of the inner ear |
|
Definition
Matching the low-impedence airborne sounds to the higher-impedance fluid of the inner ear.
**boosts the pressure measured at the tympanic membrane ~200 fold by the time it reaches the middle ear (P = F/A).
Uses the tiny foot-plate of the stapes at the oval window is much smaller than the tympanic membrane as well as the lever mechanism there to increase force output. |
|
|
Term
| Where do the neural aspects of the auditory system sit? |
|
Definition
| Within the organ of corti, found in the cochlea. |
|
|
Term
| The structures of the cochlea |
|
Definition
Cochlea - part of the inner ear.
1) Organ of corti -
a. Where all of the neural aspects are found
2) Scala vestibuli / scala tympani
a. Perilymph - similar CSF low K+, high Na+
3) Scala media
a. Endolymph, ionic concentration similar to intracellular fluid, Low Na+, High K+ |
|
|
Term
| What chambers are connected by the basilar membrane? |
|
Definition
| The scala vestibuli and the scala media. |
|
|
Term
|
Definition
| Refers to the hole in the apex basilar membrane that connects the scala tympani and scala vestibuli, allowing them to communicate. |
|
|
Term
Which part of the basilar membrane is stiffest?
a) All of it
b) The base of it
c) The apex of it
d) The middle of it |
|
Definition
|
|
Term
| Describe the shape of the basilar membrane |
|
Definition
Widens from base to apex (base narrower than apex)
Stiffness decreases from base to apex (base is stiffer than apex) |
|
|
Term
| How does frequency affect the basilar membrane |
|
Definition
Frequency determines the distance that a sound wave travels up the basilar membrane.
High frequency sound propagates little (high vibration, high dissipation of energy)
Low frequency sound propagates further (low vibration, little dissipation of energy) |
|
|
Term
| Describe the reaction of the basilar membrane to an auditory stimulation |
|
Definition
| Fluid movement bends basilar membrane at the base - this sets up a wave that travels towards the apex to the helicotrema. |
|
|
Term
|
Definition
| The bipolar spiral ganglion cells where all the auditory nerves exit the ear … leads into the auditory nerve |
|
|
Term
| Auditory sensory receptor cells |
|
Definition
Hair cells - (found with stereocilia facing the endolymph in the scala media)
There are two types: (1:3 proportion)
- Inner hair cells
- Outer hair cells (3x more)
There are stereo-cilia that actually move when sound gets to the basilar membrane. Bending in one direction causes depolarization, in the other direction causes hyperpolarization.
**these sensory cells synapse onto the spiral ganglia, with 10 spiral ganglion cells to one inner hair cell… and several outer hair cells to one spiral ganglion cell.
They use mechanical deformation of the hair cells to transduce sounds. |
|
|
Term
|
Definition
|
|
Term
| Describe auditory sensory transduction |
|
Definition
Sound waves are translated into mechanical waves by the middle ear. In the cochlea, facing the scala media, are the stereocilia of the hair cells responsible for tranducing the mechanical stimuli into electrical, out the spiral ganglion (auditory nerve).
The stereocilia are attached to each other by tip-links, which cause a mechanical deformation of the tips of the stereo-cilia when the fluid wave reaches the basilar membrane.
The deformation of the tips in a specific direction causes TRP-A1 channels to open and K+ to enter from the endolymph - depolarizing the cell and allowing for opening of voltage gated calcium channels.
Entrance of calcium allows for exocytosis of the synaptic vesicles containing NT's onto the spiral ganglion and optic nerve. |
|
|
Term
|
Definition
Involved in auditory transduction - outer and inner hair cells.
Outer hair cells function to amplify the signal in the basilar membrane.
Inner hair cells are key for signal transduction as 10 spiral ganglion cells attach to one inner hair cell. |
|
|
Term
| What is the function of the outer hair cells |
|
Definition
To amplify the sound through the basilar membrane. "double bounce" using the protein "prestin"
They have less of a function in stimuli transduction because about 10 outer hair cells innervate 1 spiral ganglion cell whereas 10 spiral ganglion cells are innervated by 1 inner hair cell. |
|
|
Term
|
Definition
| Motor protein found in outer hair cells that are required for the "double bounce" effect. |
|
|
Term
|
Definition
Hear constant ringing.
Due to burning out the outer hair cells. Since they don't work properly, there are symptoms such as clicking/ringing/and other obnoxious noises. |
|
|
Term
| What is the auditory pathway? |
|
Definition
(PRIMARY NEURONS)
Auditory receptor cells in the cochlea --> spiral ganglia --> auditory nerve fiber --> ventral/dorsal cochlear nucleus
(SECONDARY NEURONS)
Leaving from the ventral/dorsal cochlear nucleus bilaterally, it then proceeds to the inferior/superior olive nuclei.
Superior olive nuclei --> inferior culliculus
Inferior olive nuclei --> superior culliculus
(TERTIARY NEURONS)
Inferior/superior colliculus --> MGN (thalamic relay)
(FOURTH ORDER NEURON)
MGN --> auditory cortex |
|
|
Term
| Where are the bipolar cells of the auditory pathway? |
|
Definition
| They are in the spiral ganglia |
|
|
Term
|
Definition
| By number and firing rate of neurons. The louder the noise, the greater the # recruited + the faster the firing rate of neurons involved. |
|
|
Term
|
Definition
Systematic organization of characteristic frequency within an auditory structure.
Along the basilar membrane there are hair cells. Each of these hair cells are tuned to a different frequency of noise (because different points of the basilar membrane are stimulated by different frequencies).
The organization of these hair cells are maintained from the spiral ganglion back to the auditory nerve and the cochlear nucleus
Key for intermediate and high frequency sounds. |
|
|
Term
| How are low frequencies, intermediate frequencies and high frequencies represented? |
|
Definition
Low frequency ; phase locking
Intermediate frequency: phase locking + tonotopy
High frequency: tonotopy only
**ionic displacement across the membrane limits phase locking capabilities |
|
|
Term
| Where are the nuclei controlling the mechanisms of sound localization located? |
|
Definition
| In the auditory brain-stem nuclei mediate sound localization. |
|
|
Term
| Mechanism of sound localization |
|
Definition
Interaural time differences:
The medial superior olive computes the location of sound by interaural time difference <3 kHz. |
|
|
Term
|
Definition
| Computes location of a sound that are below 3Hz by interaural time differences. |
|
|
Term
|
Definition
Computes the location of a sound by interaural intensity differences.
Sound stimulates "lateral superior olive" of which ever side the sound is in first. (LSO)
This stimulus also inhibits the superior olive nucleus of the other ear via the medial nucleus of the trapezoid body (MNTB)
This makes it so that there is a greater net excitation going to higher processing centers from one side (the side which the noise arrived at first). |
|
|
Term
True or false:
Perception of the auditory space occurs in the hindbrain circuitry. |
|
Definition
| False. Perception of auditory space is synthesized by the mid-brain circuitry. |
|
|
Term
| Where is the auditory space map found? What is significant about this? |
|
Definition
Found in the colliculus.
Respond best to sounds originating from a specific region of space. Have preferred elevation/horizontal location. |
|
|
Term
| Medial geniculate complex |
|
Definition
Thalamic relay for all auditory information destined for the cortex.
Neurons in the complex receive convergent inputs from spectrally/temporally separate pathways. |
|
|
Term
True or false:
At the level of the brain stem, tonotopy is not maintained. |
|
Definition
| False. Tonopy is maintained at the level of the brain stem. |
|
|
Term
| True or false: tonopy in the cortex is by frequency |
|
Definition
|
|
Term
| Where is the primary auditory cortex located? |
|
Definition
On the superior temporal gyrus in the temporal lobe and receives point-to-point input from the thalamus.
There's a secondary, more peripheral, auditory cortex which receives more diffuse stimuli. |
|
|
Term
| Vestibular system function |
|
Definition
Perception of self-motion, head position, spatial orientation relative to gravity (vertical)
Also involved in stabilizing gaze, head and posture. |
|
|
Term
|
Definition
A part of the vestibular system.
Involved in the perception of rotational accelerations of the head. |
|
|
Term
|
Definition
Utricle and saccule
Involved with linear accelerations of the head and static position relative to gravity (vertical)
Called otolith organs because they function using a gelatinous cap covering hair cells with otoconia on top of the cap. Shearing force between the otoliths and macula densa cause displacement of hair bundles.
Head tilts, gravity causes the otolith membrane to displace relative to the sensory epithelium. |
|
|
Term
|
Definition
| Same thing as the semi-circular canal of the vestibular system |
|
|
Term
| The ganglion that innervates the vestibular nerve |
|
Definition
|
|
Term
| Vestibular hair cells - direction of depolarization |
|
Definition
|
|
Term
| The sensory epithelium of the vestibular system |
|
Definition
Ampulla
Succulus (vertical motion)
Utricle |
|
|
Term
| Vestibular hair cell transduction |
|
Definition
Hair cells have stereocili/kinocili facing the endolymph.
Shearing stress on the otoconia [and therefore the gelatinous cap covering the cilia] cause the bending of the hair cells towards the kinocili cause the opening of TRPA-1 channels that are opened by the deformation @ the tip links.
Potassium comes in, depolarizes the cell and opens voltage gated calcium channels.
Calcium influx causes exocytosis of synaptic vesicles containing neurotransmitter.
If there is enough NT's released, the Scarpa's ganglion will fire, synapsing on the vestibular nerve. |
|
|
Term
True or false:
The otolith organs are found in the semi-circular canals |
|
Definition
False.
They are found in little chambers BY the semi-circular canal. |
|
|
Term
True or false:
A head tilt is congruent with a transient displacement relative to the vestibular system |
|
Definition
False.
A head tilt would be a tonic displacement, because you actually move your head.
The transient displacement refers more to acceleration or deceleration where the head doesn't actually move relative to the vertical.
Also, remember that tonic - sustained and transient - brief. |
|
|
Term
| How does the vestibular nerve encode afferent information? |
|
Definition
Movements cause changes in firing rate.
There is a high basal firing rate --> tilting in one direction will cause an increase, tilting in the opposite will cause a decrease in firing rate.
Can signal either absolute head position or linear acceleration. |
|
|
Term
| Semicircular canal function |
|
Definition
Part of the vestibular system
Senses head rotations and angular acceleration |
|
|
Term
| Describe how the semicircular canals work |
|
Definition
They're part of the vestibular system.
The semicircular canals have structures called ampulla found near its ends.
These structures contain within them sensory epithelium called crista that contain hair cells.
The hair cells extend from the crista into another structure called the cupula..
The cupula is a gelatinous bundle containing the hair cells.
When the head turns in the plane of one of the semicirc canals, inertia of the endolymph creates a shearing stress across the cupula, distending it away from the direction of head movement + causing displacement of the hair bundles within the crista.
There is an equal and opposite movement occurring within the semicircular canals of the other ear. |
|
|
Term
In which would we expect a depolarization:
1) In the vestibular hair cells of the cupula, in the direction of head rotation
2) In the vestibular hair cells of the cupula, in the opposite direction of head rotation
3) Neither
4) Both |
|
Definition
| 1 - the hair cells in the direction which the head is moving will be depolarized, while those on the other side will be hyperpolarized. |
|
|
Term
| How does the vestibular system sense angular accelerations? |
|
Definition
The semicircular canals of the vestibular system are responsible for the interpretation of angular movement.
At the beginning of angular movement, it is encoded by an increase in the firing rate at sarca's ganglion.
At the end of the angular movement there is a sudden hyperpolarization (and sudden decrease in firing rate)
In between it normalized (so both were above or below norm). (max depolarization = acceleration. Max inhibition = deceleration) |
|
|
Term
|
Definition
| Slow eye movement that occurs opposite to head rotation. |
|
|
Term
|
Definition
Can occur because of a lack of the spontaneous firing characterized by the vestibular system. If only one ear is damaged, there will still be spontaneous firing in the other ear and the eyes will respond to this difference in firing rate as though it were responding to angular acceleration.
Characterized by a "drifting" of the eyes. |
|
|
Term
| Ganglion of the vestibular system |
|
Definition
|
|
Term
| Paramedian pontine reticular formation (PPRF) |
|
Definition
A collection of local circuit neurons responsible for generating horizontal eye movements.
Horizontal gaze center. |
|
|
Term
| Vestibulo-ocular reflex definition: |
|
Definition
| Mechanism for producing eye movements that counter head movements, permitting the gaze to remain steady while the head turns. |
|
|
Term
| Vestibulo-ocular reflex - turning your head to the right |
|
Definition
Turn head to the right:
- Positive effect on right vestibular nucleus
- Inhibitory effect on the on right-abducens nucleus and activation of the left-abducens nucleus
- Activation of the left-abducen's nucleus causes the stimulation of the left-lateral rectus muscle and the right medial rectus muscle.
- This initiates eye movement to the left. |
|
|
Term
| Which cortex is (are) involved with vestibular information? |
|
Definition
There are two vestibular corticies!
1) Just posterior to the primary somatosensory cortex
2) Transition between somatic sensory cortex and the motor cortex |
|
|
Term
| What are the cortical areas involved with planning and executing movements? |
|
Definition
Prefrontal cortex - area for making the decision about movement. 'planning neurons'
Supplementary motor areas (SMA) and premotor areas (PMA) - coordinate the actual movement.
M1 - the primary motor cortex --> center for initiating movement. |
|
|
Term
| Supplementary motor area and premotor area |
|
Definition
| Coordinate the actual movement between the prefrontal cortex and the motor cortex. |
|
|
Term
| Which ganglia regulate the upper motor neurons |
|
Definition
|
|
Term
| Which ganglia or neuron is damaged in parkinsons or huntingtons disease? |
|
Definition
|
|
Term
| Components of the basal ganglia? |
|
Definition
Substantia nigra
(very important in parkinsons disease)
Striatum: (the input of the basal ganglia)(medium spiny neurons)
Caudate nucleus (controls eye movements)
Putamen (functions other than eye movements)
Subthalamic nucleus (sorts and leads to output)
Globus pallidus
VL nucleus of the thalamus. |
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Term
| Where are the substantia nigra compacta and substantia nigra reticulata located? What are they associated with? |
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Definition
They are located within the midbrain.
They are involved with the basal ganglia components. |
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Term
| Describe the basal ganglion loop |
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Definition
1) begins in the cerebral cortex.
2) Caudate/putamen
3) Caudate to Substantia nigra pars compacta (cell bodies here)
4) Putamen to globus palladus internal
5) Substantia nigra pars compacta --> to --> superior colliculus
1. And back to caudate - but this is dopaminergic!
6) Globus palladus internal --> VA/VL complex (thalamus)
7) VA/VL complex (thalamus) --> frontal cortex |
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Term
| What type of NT does the substantia nigra release? |
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Definition
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Term
Where do the following synapse on a medium spiny neuron: ***
a) Cortical neurons
b) Interneurons / thalamus (local circuit neurons)
c) Substantia nigra pars compacta |
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Definition
A - on the dendritic spines -->
B - on the dendritic shafts, near the cell soma
C - at the base of the spine |
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Term
| The firing of medium spiny neurons occurs when, all the time or periodically? |
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Definition
They are normally silent.
However, they become active when there is movement. |
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Term
| When do putamen neurons fire |
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Definition
| In anticipation of body movements. |
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Term
| When do caudate neurons fire? |
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Definition
| In anticipation of eye movements. |
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Term
| What are medium spiny neurons involved in the initiation of? |
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Definition
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Term
| What are the medium spiny neurons and where do they synapse? |
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Definition
The medium spiny neurons are of the caudate/putamen nuclei.
They synapse onto either the globus pallidus internal or the substantia nigra pars reticulata.
Caudate is involved with eye movements --> the substantia nigra is involved with eye movements.
Putamen nuclei is involved with other movements --> the globus pallidus internal. |
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Term
| Where does the globus palladus internal synapse? |
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Definition
The globus pallidus internal is a component of the basal ganglia component pathway.
It synapses on the VA/VL complex of the thalamus.
From there, it goes to the frontal cortex. |
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Term
Match the following with the rest:
a) Caudate nucleus
b) Putamen nucleus
c) Substantia nigra pars reticulata
d) Globus pallidus internal
e) VA/VL complex (thalamus)
a) GABAergic
b) Cholinergic
c) Adrenergic
d) Dopaminergic
e) Glutaminergic |
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Definition
A - GABA
B - GABA
C - GABA
D - GABA
E - glutaminergic |
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Term
| True or false: the main output of the basal ganglia is inhibitory |
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Definition
True!
It takes inhibition of inhibition to cause an excitation response! |
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Term
True or false:
The substantia nigra pars reticulata and the globus pallidus internal are constantly tonically firing. |
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Definition
True.
They're constantly firing in order to inhibit unwanted movement.
It is disinhibition that allows movement to occur. |
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Term
What is the direct pathway through the basal ganglia.
What's the point of this pathway? |
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Definition
The direct pathway refers to the pathway from:
Cortex information --> caudate/putamen --> substantia nigra parts reticulatum / globus palladus internal
The point of this path is to release inhibition of inhibition to incite movement. |
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Term
What is the indirect pathway through the basal ganglia?
What's the point of this pathway? |
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Definition
Cortex --> caudate/putamen (GABA) --> globus pallidus external (GABA) --> subthalamic nucleus (Glut) ---> globus pallidus internal (GABA)
The point is to stimulate the inhibitory influences on the upper motor neurons.
"break" on the direct pathway. |
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Term
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Definition
| Violent, involuntary movements of the limbs, is the damage to the subthalamic nucleus - occurs on only one side of the body. |
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Term
| Damage to the sub-thalamic nucleus can cause what condition? |
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Definition
| Hemiballismus -- violent, involuntary movements of the limbs. |
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Term
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Definition
Hyperkinetic disorder.
Results from the degeneration of the medium spiny neurons (caudate and putamen) that project into external segment of the globus pallidus.
This produces a reduction in the inhibitory outflow of basal ganglia. This makes it so that upper motor neurons can be activated by inappropriate signals, producing undesired ballistic, choreic movements. |
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Term
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Definition
Part of the direct basal ganglion pathway:
Excitatory dopaminergic receptor found on the spiny cells of the substantia nigra that project into the internal segment of the globus pallidus.
Overall effect: decrease in inhibitory outflow of basal ganglia and increase the excitability of upper motor neurons. |
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Term
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Definition
Part of the indirect basal ganglion pathway:
Inhibitory input receptor found on the spiny cells of the substantia nigra that project to the external globus pallidus. |
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Term
| Damage to what brain structure is a hallmark of parkinson's disease? |
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Definition
| Substantia nigra is largely absent in parkinson's disease. |
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Term
| True or false: a reduction in dopamine will result in an increase in activity because of a reduction in inhibition. |
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Definition
False. A reduction in dopamine will result in a decrease in movement overall.
The substantia nigra, which is typically damaged in people with parkinsons, resulting in a reduction in dopaminergic neurons. |
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Term
| What causes the hyperkineticness of parkinsons disease |
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Definition
| There is a destruction of the substantia nigra. This results in an abnormally high inhibitory outflow of the basal ganglia. |
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Term
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Definition
| Sensory neural processes of encoding and processing noxious stimuli, depends on specifically dedicated receptors and pathways distinct from sensory processing of ordinary mechanical stimulation. |
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Term
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Definition
| Free nerve endings that are relatively unspecialized that initiate the sensation of pain. |
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Term
Which has the larger receptor field:
Mechanoceptors or nocioceptors |
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Definition
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Term
| What are the major classes of nocioceptors in the skin. |
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Definition
A-delta nocioceptors (mechanical)
A-delta thermal nocioceptors (>45*C or <5*C)
C-fiber polymodal nocioceptors (mechanical/chemical/thermal)
**often work together to give the perception of pain. |
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Term
True or false:
The major classes of nocioceptors are uni-polar neurons |
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Definition
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Term
| Where do the afferent nocioceptors synapse onto? |
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Definition
| They synapse into the spinal cord onto secondary neurons. |
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Term
Put the following in order of fastest conducting neuron:
a-alpha
a-beta
a-delta
C |
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Definition
| A-alpha > a-beta > a-delta > C |
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Term
| Which neuron is pivotal in the "fast neuron pathway" |
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Definition
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Term
| Which neuron is pivotal in the "slow neuron pathway" |
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Definition
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Term
| Which is myelinated, C or A-delta fibers? |
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Definition
A-delta fibers are myelinated
C fibers are not. |
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Term
What are each of the following fiber types involved in:
A-alpha
A-beta
A-delta
C |
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Definition
a-alpha
- Proprioception of skeletal muscle
a-beta
- Mechanoreceptors of the skin
a-delta
- Pain, temperature sensation
C
- Temperature, pain and itch sensation |
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Term
Which is faster:
Proprioception, nocioception or mechanoception |
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Definition
Nocioception is the slowest.
Proprioception is the fastest. Mechanoception is the next fastest. |
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Term
| The delayed, longer lasting dull ache that you get after an injury is caused by which neuronal fibers? |
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Definition
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Term
| The immediate, sharp pain response is caused by what neuronal fiber |
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Definition
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Term
| True or false: pinching off the oxygen flow to C-delta fibers will cause them to be inhibited. |
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Definition
False! Anoxic conditions affect A-delta fibers before they do C-delta fibers.
If you want to inhibit C-delta fibers, you can use certain neurotoxins. |
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Term
| What is the mechanism by which the nerve endings of nocioceptors are depolarized and action potentials are generated |
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Definition
This is not actually well known!
However, it's thought that TRPV-1 channels are involved. These are the receptors that are stimulated by capsaicin, the primary component that makes hot peppers hot. |
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Term
| TRPV-1 receptors are stimulated by what? |
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Definition
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Term
| TRPV-1 is highly expressed with what other channel? |
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Definition
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Term
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Definition
| Noxious cold receptor that is both chemo- and mechanosensitive. |
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Term
| What makes TRPA-1 receptors mechanosensitive |
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Definition
| The ankyrin repeats - when tissues surrounding it compress, it forces the channel open. |
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Term
| Which TRP channels are within the noxious range? |
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Definition
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Term
| Acid sensing ion cannels (ASIC) |
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Definition
ASIC 1-4 nocioceptors found, ASIC 3 most common.
Selectively permeable to Na. (role in firing AP's)
Highly localized in nocioceptors innervating joints and muscles. Senses acidity changes (lactic acid) |
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Term
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Definition
P2X and P2Y - activated by ATP released by tissues - are Na and Ca permeable.
P2X - ligand gated ion channels that are highly expressed in nocioceptors
P2Y - g-protein coupled receptors that can modify a signal by interacting with other channels. |
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Term
| Where are the cell bodies for pain fibers found? |
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Definition
| In the dorsal root ganglia, entering into the spine. |
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Term
| Where do the primary axons of nocioceptors exist? |
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Definition
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Term
| Where do facial nocioceptors enter into the spinal cord? |
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Definition
| Enter through the trigenital ganglion |
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Term
| Where is the dorsal horn? |
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Definition
| In the spinal cord - this is where primary nocioceptive neurons synapse onto secondary ones. |
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Term
| Where do afferent nocioceptive fibers terminate in the dorsal horn? |
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Definition
a-delta fibers --> synapse lamina 1 and 5
C fibers --> lamina 2
A-beta fibers --> lamina 4 (mechanoreception)
*however this is just a general trend, not set in stone.
**this is where they synapse onto secondary neurons. |
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Term
| Neural basis for referred pain |
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Definition
Due to a convergence of somatic and visceral nociceptive input to the substantia gelatinosa.
*a single projection neuron receives input from both regions, synapsing onto the same projection (in the dorsal horn) |
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Term
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Definition
| A condition in which pain from injury to a visceral structure (Ie the heart) is displaced to other areas of the body (IE the left arm) |
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Term
True or false:
Interactions between proprioceptors within the dorsal horn can module the transmission of nocioceptive information to higher centers. |
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Definition
False.
Mechanoreceptive afferents, not proprioceptive afferents, are the ones that can module that information. |
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Term
| Why is there reduced pain while rubbing an injury |
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Definition
| The stimulation of low-threshold mechanoreceptors causes a modulation of the nocioceptive information being transmitted to higher centers. They do this through local interactions in the dorsal horn. |
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Term
| Nocioceptive afferents use what as neurotransmitters? |
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Definition
Glutamate and neuropeptides.
Glutamate = from translucent vesicles *fast EPSP
Neuropeptides = dense-core vesicles *substance P, slow EPSP |
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Term
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Definition
Repeated application of noxious stimuli causes nearby nocioceptors that were previously unresponsive to become responsive to mechanical stimuli.
Especially thermal injury. |
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Term
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Definition
The inflammation that occurs around the injury-specific.
Caused by neuropeptides that get released from the neurons. Flare is often sensitized. |
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Term
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Definition
Results from the interaction of nocioceptors with the substances released when tissue is damaged.
Ex of metabolites released:
Extracellular protons, arachidonic acid/lipid metabolites, bradykinin, histamine, serotonin, prostaglandins, nucleotides, nerve growth factor (NGF) |
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Term
| How do metabolites increase or cause sensitization |
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Definition
Metabolites released by tissue damages cause sensitization by interacting with receptors or ion channels of nocioceptive fibers, augmenting their response by decreasing the threshold for activation.
(prostaglandins) |
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Term
| How do prostaglandins affect pain sensation? |
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Definition
| Prostaglandins reduce the threshold for activation by phosphorylating sodium channels and causing them to open. |
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Term
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Definition
Refers to a nocioceptive phenomenon.
Nocioceptive stimulus goes to the spine, reflecting down other branches of the nocioceptive fiber where, at the tips, there are metabolites found and released that cause increased sensitization. |
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Term
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Definition
| Compounds that reduce pain intensity |
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Term
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Definition
| Nonsteroidal anti-inflammatory drugs |
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Term
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Definition
| Act by inhibiting COX, an enzyme key for the production of prostaglandins. |
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Term
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Definition
| When types of noxious stimuli cause such sensitization that normal noxious stimuli, such as a small scratch, are perceived as abnormally high degree of pain or spontaneous pain. |
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Term
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Definition
Occurs at the synapse level where there's sensitization of the primary afferents, decreasing the threshold for activation of nocioceptor neurons.
They become hyperexcitable and cause frequent firing |
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Term
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Definition
| Activity dependent increase in the excitability of neurons in the dorsal horn of the spinal cord. Occurs following high levels of activity in the afferent neurons. |
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Term
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Definition
| Induction of pain by what is normally an innocuous stimulus. |
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Term
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Definition
Activity-dependent plasticity characterized by progressive increase in firing from dorsal horn neurons during train of repeated C-fiber or nocioceptor stimulation.
Occurs from summation of synaptic potentials.
Allows for removal of Mg block from NMDA channels, allowing influx of Ca and allowing the insertion of AMPA receptors into the membrane. |
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Term
| Homosynaptic facilitation |
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Definition
| Potentiation of a neuron that impacts itself. |
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Term
| Heterosynaptic facilitation |
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Definition
| Potentiation of a neuron that impacts the neurons around it, also potentiating them. |
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Term
| Why does the phantom limb phenomenon occur? |
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Definition
Functional reorganization of the somatotopic maps in the primary somatosensory cortex occurs in amputees.
The sensation is displaced to a different area of the body |
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Term
| How can you treat phantom limb? |
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Definition
| The mirror technique - helps to reformat your somatotopic maps by tricking your brain into thinking that you're moving the hand that is missing, even though you're moving the hand that you have left in the mirror, to make it look like the other hand. |
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Term
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Definition
Part of the anterolateral system. Goes from the spine to the thalamus. Part of the somatosensory pathway for pain, temperature and some touch -- the primary targets are the primary and secondary somatosensory cortex.
Within the dorsal root, primary sensory neurons synapse onto secondary neurons. Secondary neurons then cross the midline going up to the thalamus and then the primary/secondary sensory cortex. |
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Term
| Dorsal-column-medial lemniscal pathway |
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Definition
Type of somatosensory tract (alongside spinothalamic) - carries information about touch, vibration, discrimination and proprioception.
Primary neuron enters into the spine, continues up the tract on the dorsal side then synapses onto a secondary neuron at the level of the medulla and crosses over the medial line before crossing over to the other side to the thalamus (VENTRAL POSTERIOR NUCLEUS) then the primary and secondary somatosensory cortex. |
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Term
| What are the major ascending pathways for somatic sensation? (ANTEROLATERAL SYSTEM) |
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Definition
| The dorsal-column-medial lemniscal pathway and the spinothalamic tract. |
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Term
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Definition
Incomplete spinal cord lesion characterized by clinical presentation reflecting hemisection of the spinal cord.
Can cause you to lose different sensations of nocioception and mechanosensation to different parts of the body.
Specifically:
Nocioception: sensation below the damage is reduced contralateral to the damage.
Mechanoception: sensation below the damage, but on the same side, is reduced. |
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Term
| Pain perception --> neural pathway |
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Definition
| Primary nocioceptor gets activated, impulse travels up towards spinal cord, enters dorsal horn of spinal cord and synapses on secondary neuron, it crosses over and goes up the spinothalamic tract to the thalamus which then triggers mainly the primary and secondary somatosensory cortex. |
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Term
| Projections from the anterolateral system onto the following are important for what? Where do they synapse onto? |
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Definition
Goes to the medial thalamic nuclei
This provides nocioceptive signals to areas in the insular cortex and the cingulate cortex. |
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Term
| What are the additional cortical areas involved with pain perception? |
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Definition
| Cingulate and insular cortex. |
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Term
| What are the components of pain perception? |
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Definition
1) Sensory discriminative component: signals the location, intensity and quality of noxious stimuli. (somatosensory areas of cortex)
2) Affective-motivational component: signals the unpleasant quality of the experience and enables autonomic activation that follows a noxious stimuli.
(brainstem and additional cortical areas) |
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Term
True or false:
Hypnosis is a valid and effective way of reducing perception of pain |
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Definition
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Term
| Which neurological structure is associated with the emotional aspect of pain |
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Definition
| Cingulate cortex - it's part of the limbic system. |
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Term
| Changes in pain intensity are accompanied by what neural changes? |
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Definition
| Changes in pain intensity are accompanied by changes in activities in the somatosensory cortex. |
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Term
| Changes in pain unpleasantness are accompanied by what neural changes? |
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Definition
| A change in unpleasantness is accompanied by a change in activities in the cingulate cortex. |
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Term
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Definition
| Processes information about the internal state of the body. |
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Term
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Definition
Noxious stimuli produce pain but there is no appropriate emotional response that goes with it.
"false alarm theory" could explain why this happens |
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Term
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Definition
Part of the affective-motivational aspect of pain.
Mediated by projections to the reticular formation of the midbrain (parabrachial nucleus) into the hypothalamus and the amygdala. |
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Term
| The interpretation of pain |
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Definition
| The difference between the objective reality of a painful stimulus and the subjective response to it. |
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Term
| True or false: opiates work by blocking the ascending tract of pain |
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Definition
| False! They work by blocking the descending pain-modulating pathways. |
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Term
| Periaqueductal gray of the midbrain |
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Definition
Part of the physiological basis for pain modulation.
Electrical stimulation at this point produces anelgesic type effects that inhibit the activity of nocioceptive projection neurons in the dorsal root of the spinal cord. |
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Term
| True or false: opioids affect only at the site of secondary neurons |
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Definition
| False. It affects both primary and secondary neurons. |
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Term
| What do opioids do to the overall pain response? |
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Definition
| It decreases the magnitude and duration of the pain response. |
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