Term
| does the basal ganglia have direct projections to the motor neurons? |
|
Definition
|
|
Term
| what are the basal ganglia? |
|
Definition
Large, functionally diverse set
of subcortical nuclei. Receives inputs from cortical
structures and sends outputs
back to prefrontal, premotor,
and motor cortices |
|
|
Term
| what are the parts of the basal ganglia? |
|
Definition
Striatum (caudate and
putamen)
–Globus pallidus or
pallidum (GPi, GPe, some
books include substantia
nigra pars reticulata)
–Substantia nigra
–Subthalamic nucleus |
|
|
Term
| substantia nigra pars compacta has what? |
|
Definition
| dopaminergic cells producing dopamine (involved in parkinson's disease) |
|
|
Term
| where does the basal ganglia recieve inputs from? where does it send its signals? |
|
Definition
| it recieves inputs from the entire cortex EXCEPT the primary visual cortex and primary auditory cortex. it sends its signals to the thalamus and the midbrain |
|
|
Term
| what part of the basal ganglia receives the inputs? |
|
Definition
| the caudate and putamen (together called the striatim) |
|
|
Term
Inputs to the corpus striatum synapse onto medium spiny neurons. Medium spiny
neurons have large dendritic trees that allow them to integrate inputs from what parts of the CNS? |
|
Definition
| cortical, thalamic, and brainstem structures |
|
|
Term
| what are Medium spiny neurons (MSNs)? |
|
Definition
have large
dendritic trees that integrate information from
converging input. MSNsremain quiescent in absence of inputs |
|
|
Term
| where do the MSN's send their projections? |
|
Definition
| to the substantia nigra pars reticulata and globus pallidus (internal and external) |
|
|
Term
| what are the GABAergic (inhibitory) cells of the BG? |
|
Definition
|
|
Term
|
Definition
| The globus pallidus and substantia nigra pars reticulata are collectively referred to as the pallidum |
|
|
Term
1.is the pallidum a major input or output center of the BG?
2. are pallidum cells quiescent (transient) or tonic (always on)
3. is the pallidum normally inhibitory or excitatory?
4. which neurotransmitter does it use? |
|
Definition
1. output
2. tonic
3. inhibitory
4. GABA |
|
|
Term
| describe how a motor command affects the striatum, globus palladus, thalamus, and motor cortex |
|
Definition
|
|
Term
| what is the superior colliculus |
|
Definition
| these are the upper motor neurons that control saccades. the superior colliculus receives its inputs from the substantia nigra pars reticula |
|
|
Term
| Substantia nigra pars reticulata is part of the output circuitry of the BG; where does it send its outputs? |
|
Definition
| to the superior colliculus |
|
|
Term
| the direct pathway facilitates the direction of volitional movement, but the indirect pathway works to suppress what? |
|
Definition
|
|
Term
| what is the direct pathway (give the pathway and explain how it directs movement) |
|
Definition
| cerebral cortex input + Dopamine (release from substantia nigra pars compacta) action on D1 receptors to the striatum, inhibits the globus pallidus internal, which stops inhibiting the thalamus, which can stimulate the frontal cortex |
|
|
Term
| what is the indirect pathway (give the pathway and explain how it supresses unwanted movements) |
|
Definition
|
|
Term
| subthalamic nucleaus is excitatory, so it uses what neurotransmitter? |
|
Definition
|
|
Term
| Direct pathway release thalamic neurons from tonic inhibition so they can do what? |
|
Definition
| drive upper motor neurons |
|
|
Term
| Indirect pathway antagonizes activity of the direct pathway. what is its net effect? |
|
Definition
| Net effect of activity in indirect pathway is to increase the inhibitory influences of BG |
|
|
Term
| Hyperdirect pathway does what? |
|
Definition
|
|
Term
| one effect of dopamine is to ????? |
|
Definition
|
|
Term
Substantia Nigra Pars Compacta neurons can provide excitatory inputs to spinal cells that project to GPi neurons (D1 receptors) [Direct Pathway]
• these Same neurons provide inhibitory inputs to where? |
|
Definition
to spiny cells that
project to GPe neurons (D2 receptors) [Indirect Pathway] |
|
|
Term
| Both D1 and D2 receptors are metabotropic receptors. what type of mechanism do they use? |
|
Definition
both use G‐protein coupled receptors
–D1 receptors coupled to G‐proteins that stimulates cAMP
production
–D2 G‐proteins inhibit cAMP |
|
|
Term
Parkinson’s disease
• Hypokinetic movement disorder
• Caused by loss of nigrostriatal dopaminergic neurons
can you describe how parkinsons effects both D1 and D2 pathways? |
|
Definition
–Normal dopamine release in corpus striatum increases responsiveness of direct pathway to corticostriatal input
(D1 effect) while decreasing responsiveness of the indirect
pathway (D2 effect) |
|
|
Term
When dopaminergic cells of pars compacta are destroyed (PD), inhibitory outflow of BG is abnormally
high. what is the net effect of this ? |
|
Definition
–Failure of thalamic disinhibition normally mediated by BG
–Thalamic activation of UMNs in motor cortex is less likely
for parkinsons, we end up with greater activation of the GPinternal (the brake) so we get less thalamic activity even with direct stimulation |
|
|
Term
| what are some signs and motor problems associated with parkinson's disease? |
|
Definition
3 cardinal signs:
– Tremor at rest ~3‐6 Hz
– Rigidity (“cogwheel”)
– Bradykinesia
• Associated motor problems
– Abnormal postural reflexes
– Masked face
– Festination
– Stooped posture
– Paucity of associated movements
– Micrographia
– Diminished frequency and
amplitude of saccades
– Hypophonia |
|
|
Term
| huntington's disease is due to degeneration of what? |
|
Definition
| medium spiny neurons that project to external segment of globus pallidus (indirect pathway.) |
|
|
Term
| so how does huntington's disease cause this increase in movement? |
|
Definition
| so we get an increase in activity of the GP internal segment ( taking the foot off the brake), so we get a lot less tonic inhibiton of the thalamus, so we get jerky movements. |
|
|
Term
| Cerebellum function: you learn how to correct for those gravitational interactions of joints. |
|
Definition
| for example: when walking you don't need to use your hamstring because you your hip flexes forward quickly, your knee flexes a bit on its own from gravity. |
|
|
Term
| what are the anatomical parts of the eye? |
|
Definition
Sclera/cornea
• Sclera – tough outer CT layer; forms visible white portion
• Cornea – anterior, transparent permits light transmission
– Choroid/ciliary body/iris
• Choroid - underneath sclera, vasculature
• Choroid layer, anterior to forms ciliary body and iris
– Retina
• Outer pigmented layer
• Inner neural (rods/cones) |
|
|
Term
| what are the fluid filled cavities of the eye? |
|
Definition
Posterior (lens/retina) - vitreous humor
– Anterior cavity (cornea/lens) – aqueous humor. nutrients,
capillary network with ciliary body |
|
|
Term
|
Definition
Controls amount of light entering
– 2 smooth muscle networks
• Circular (or constrictor) muscle
• Radial (or dilator) muscle
– Pigmented = eye color
– Unique ID |
|
|
Term
| does the cornea affect the refraction of light? |
|
Definition
| yes, in fact LASIK alters the shape of the cornea (because the lens muscles don't work as well and the lens can change shape, so we just change the shape of the cornea) |
|
|
Term
| what are the 3 excitable layers of the retina? |
|
Definition
Outermost layer - rods and cones
– Middle layer - bipolar cells
– Inner layer - ganglion cells, axons = optic nerve
• optic nerve leaves is the optic disc
• blind spot - no image can be detected (no rods/cones) |
|
|
Term
| horizontal and amacrine cells are more for lateral inhibition |
|
Definition
|
|
Term
|
Definition
Pinhead-sized depression
center of retina,
• most distinct vision (only
cones) (cones = color, rods = black/white) |
|
|
Term
| what is the macula lutea? |
|
Definition
immediately surrounds the fovea, high actuity.
• Degeneration – 1 cause of
blindness in West,
“doughnut vision" |
|
|
Term
| what are the photopigments? |
|
Definition
Opsin - integral disc membrane protein
– Retinene -Light-absorbing (vitamin A derivative) |
|
|
Term
| what are some differences between rods and cones? |
|
Definition
Rods:
100 million per retina
vision in shades of gray
high sensitivity
low acuity
night vision
high convergence in retinal pathways
more numerous in periphery
Cones:
3 million per retina
color vision
low sensitivity
high acuity
day vision
low convergence in retinal pathways
concentrated in the fovea |
|
|
Term
| how does processing of rods and cones work? what compounds are involved? |
|
Definition
Dark= high GMP, Na
channel open -depolarization, release
inhibitory transmitters to
bipolar cell (inhibit cells)
– Light = low GMP, Na
channels close –
hyperpolarization, stop
inhibitory transmitter release
(removal of inhibition) |
|
|
Term
| what is the function of a bipolar cell? |
|
Definition
excitability transmits to
ganglion cells
– propagation to visual cortex |
|
|
Term
| how do you regulate light entry? (dark exposure vs light exposure) |
|
Definition
Dark exposure
•sympathetic radial dilator activity (also distance vision)
• dark adaptation – reconstitution of rod photopigments broken
down by previous light exposure
• Light exposure
•parasympathetic constrictor activity (also near vision
• light adaptation - rapid breakdown of cone photopigments |
|
|
Term
| right visual field information (FROM BOTH EYES) goes to where in the brain? |
|
Definition
| the left lateral geniculate nucleus of the thalamus and then it goes to the occipital lobe for processing. |
|
|
Term
| what are ocular dominance columns? |
|
Definition
| this is where you integrate both eye's information. |
|
|
Term
| pituitary gland sits where in the brain? |
|
Definition
| right on top of the optic chiasm |
|
|
Term
| with a lesion to the optic chiasm, what part of the visual field would you lose? |
|
Definition
| you would lose the periphery, just have the middle of the field |
|
|
Term
| with a lesion of the left optic tract, what will you see? |
|
Definition
| you will ONLY see the left visual field |
|
|
Term
| what are the parts of the ear? |
|
Definition
External ear
– Consists of pinna, external
auditory meatus, and tympanum
– Transmits airborne sound waves to
fluid-filled inner ear
– Amplifies sound energy
• Middle ear
– Transmits airborne sound waves to
fluid-filled inner ear
– Amplifies sound energy
• Inner ear
– Cochlea - receptors for sound
wave detection
– Vestibular apparatus - equilibrium |
|
|
Term
| give me a quick overview of sound wave transmission |
|
Definition
the tympanic membrane oscillates which shakes the malleus incus and stapes on the oval window, which causes waves in the cochlear fluid. the vibrations in the fluid move the paralymph and endolymph of the basilar membrane or vestibular membrane. Receptive hair cells bent as basilar
membrane is deflected up and down
– Stereocilia contact overlying tectorial
membrane (stationary)
– Bending opens mechanically-gated
channels – receptor potentials generated |
|
|
Term
| what are some taste buds? |
|
Definition
Sweet - glucose (K+ channel closure)
Sour – H+ ions – blocks K+ channels
Salty – specialized Na+ channels (NaCl)
Bitter – diverse alkaloids, poisons
Umani - glutamate/MSG
Fat ? – long chain FFA |
|
|
Term
| how do taste sensations get transmitted to the brain? |
|
Definition
Receptor potential initiates APs within afferent fibers
– Facial CN– ant.. 2/3 tongue
– Glossopharyngeal CN – post 1/3 tongue, pharynx
• Synaptic connections in brain stem and thalamus to
cortical gustatory area (parietal lobe – near S1 tongue
area), hypothalamic, limbic system |
|
|
Term
| how does the sense of smell work? |
|
Definition
Olfactory mucosa - 3cm
2
of mucosa in ceiling of nasal
cavity
– Olfactory receptor cell/afferent-receptor in olfactory mucosa in
nose (axons are olfactory nerve)
– Supporting cells – mucus secreting
– Basal cells – precursor (~ 2 months)
• “Odorants” must be volatile, and water soluble
– 1000 different types of receptors
– second-messenger pathways to trigger APs
– Afferent signals are sorted according to scent component by
glomeruli within olfactory bulb |
|
|
Term
|
Definition
| The glomerulus (plural glomeruli) is a spherical structure located in the olfactory bulb of the brain where synapses form between the terminals of the olfactory nerve and the dendrites of mitral, periglomerular and tufted cells. |
|
|
Term
| how are olfactory impulses processed? |
|
Definition
Odors dissected into components
– detected by multiple
receptors/glomeruli
– G protein, cAMP, Na channel
transduction
• Olfactory bulb – above bone layer
(cribiform plate of ethmoid)
– Glomeruli and mitral cells
– Odor discrimination based on
“patterns” of glomerular
excitation
• Limbic system
– Primary olfactory cortex of
temporal lobe
– Via thalamus |
|
|
Term
| what is the vomeronasal organ? |
|
Definition
Common in mammals but until recently
was thought to nonexistent in humans
• ½ inch inside nose next to vomer bone
• Detects pheromones
– Nonvolatile chemical signals passed
subconsciously from one individual to
another
– Role in human behavior not entirely clear
• Steroidal agents can alter ANS
(increased HR, decr respiratory rate)
• pulsatile release of sex hormones
(gonadotropins) |
|
|
Term
| every cranial nerve is part of the peripheral Nervous system EXCEPT which one? |
|
Definition
| the optic nerve, which is 100% in the CNS |
|
|
Term
| what are the parts of the vestibular apparatus? |
|
Definition
Semicircular canals –
Utricle and saccule
cupula |
|
|
Term
| how does the vestibula sense linear acceleration (gravity)? |
|
Definition
neural signals generated in response to
mechanical deformation of hair cells
(kinocilium and stereocilia)
Kinocilium and stereocilia
– Semicircular canals – cupula
– Utricle/saccule
Movement triggered by fluid
movement or particle movement
– Endolymph
– Otolith (Ca crystals embedded) |
|
|
Term
| what are the little hairs on the vestibula? |
|
Definition
| Kinocilium and stereocilia |
|
|
Term
| what is the utricle and saccule of the vestibula? |
|
Definition
| While the semicircular canals respond to rotations, the otolithic organs sense linear accelerations. Humans have two on each side, the utricle and the saccule. Calcium carbonate crystals get displaced during linear acceleration, which in turn deflects the ciliary bundles of the hair cells and thus produces a sensory signal. Most of the utricular signals elicit eye movements, while the majority of the saccular signals projects to muscles that control our posture. |
|
|
Term
|
Definition
| the fluid in the semicircular canals |
|
|
Term
|
Definition
|
|
Term
1. when the stereocilia hairs bend toward the kinocilum, you get what?
2.when the stereocilia bend away from the kinocilium, you get what? |
|
Definition
1.a depolarization and increase in APs,
2. hyperpoloarization and a decrease in dishcharge |
|
|
Term
| what are the vestibular inputs? |
|
Definition
vestibular nuclei in brain
stem
Superior/medial from
semicircular and otolilths –
output to Medial
Longitudinal Fasciculs
(MLF)
Lateral (Dieter’s nucleus)
projects to lateral
vestibulospinal tract -
Descending nucleus input
from otolisths – projects to
cerebellum/RF and SC (waking up when you get a change in acceleration like when you are sleeping in a car) |
|
|
Term
| what is the MLF medial longitudinal fasciculus- it is occulomotor 3, trochlear 4, abdusens 6, |
|
Definition
| this is the place that the vestibula outputs to, all the occulomotor things so we can tell our eye its position and what direction to look. |
|
|
Term
| vestibular apparatus controls a lot of what type of muscles in the legs? |
|
Definition
| extensors (tells you how hard to push down) |
|
|
Term
| what is the PPRF paramedian pointine reticular formation and the rostral interstitial nucleus |
|
Definition
| both go to the medial longitudinal fasciulus and control sacaddic eye movements. |
|
|
Term
| what are the 3 major vestibular reflexes? |
|
Definition
Vestibulo-ocular reflex – keep the eyes still in space when the head
moves.
Vestibulo-colic reflex – keeps the head still in space – or on a level
plane when you walk.
Vestibular-spinal reflex – adjusts posture for rapid changes in
position. |
|
|
Term
| what are some descending vestibular spinal tracks? |
|
Definition
•Descends the ipsilateral spinal
chord
•Terminates at all levels of the spine.
•Excitatory pathway activates
postural muscles (proximal to spine)
to correct for leftward listing
-•Descends ipsilateral and
contralateral spinal cord but
asymmetrically
•Terminates in the cervical and
thoracic spine.
•Excitatory pathway activates
postural muscles (proximal to spine)
mainly in the neck. |
|
|
Term
|
Definition
•Both direct contralateral and indirect ipsilateral control
of extra ocular muscles
•Counters head movements to keep image stable on
retina.
•Damage of vestibular nerve/nuclei causes nystagmus a
oscillation of horizontal eye movement PPRF and trochlear all coordinate with the MLF |
|
|
Term
Optokinetic nystagmus – elicted by moving object that produce
illulsion or head movement (visual ocular response) |
|
Definition
|
|
Term
|
Definition
| Vergence – aligns fovea of each eys with targets and different distances. conjugate eye movement. |
|
|
Term
|
Definition
| Smooth pursuit – keep moving stimuli on fovea |
|
|
Term
|
Definition
| saccades – ballistic movements that abruptly change point of fixation |
|
|
