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The Diencephalon
Test 4 Material
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Graduate
03/27/2011

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Term
A nuclear complex with several major subdivisions
Definition
Diencephalon
Term
The diencephalon is composed of structures located where?
Definition
The rostral end of the brain stem
Term
Encompasses the area of the brain which extends from the posterior commissure to the interventricular foramen, and which is bounded laterally by the posterior limb of the internal capsule, and the tail of the caudate nucleus.
Definition
Diencephalon
Term
The diencephalon is separated into two symmetrical halves by what?
Definition
3rd Ventricle
Term
What is present in 70-80% of all human brains?
Definition
Massa Intermedia (Interthalamic Adhesion)
Term
Represents an area of thalamic continuity medially
Definition
Interthalamic adhesion (massa intermedia)
Term
The diencephalon consists of several specific subdivisions which include the following: (5)
Definition
1. Epithalamus
2. Thalamus
3. Subthalamus
4. Hypothalamus
5. 3rd Ventricle
Term
Portions of the epithalamus are intimately related to what system?
Definition
Limbic System
Term
The epithalamus contains several neural structures including what? (2)
Definition
Nuclei
Fiber Tracts
Term
What is one very important structure of the epithalamus?
Definition
Pineal Gland (Epiphysis)
Term
A small, cone-shaped body that is attached to the roof of the 3rd centricle near the posterior commissure
Definition
Epiphysis (Pineal Gland)
Term
Name 2 things included in the pineal gland (epiphysis)
Definition
Glia cells
Pinealocytes
Term
Unique secretory cells located within the pineal gland.
Definition
Pinealocytes
Term
The functions of the epiphysis are not fully known but what do we know about its function?
Definition
It is involved in functions that are influenced by circadian rhythmicity, such as the production of melatonin and certain neurotransmitters
Term
What can destroy pinealocytes and alter the onset of pubertal changes?
Definition
Peripubertal tumors
Term
A process which typically occurs after approximately 20 years of age
Definition
Calcification
Term
After what does the epiphysis serve as a marker for midline structures on radiograph
Definition
calcification
Term
Which area of the diencephalon is riddled with fibers and contains zona incerta and a subthalamic nucleus
Definition
Subthalamus
Term
A scattered group of cells located in the subthalamus
Definition
Zona Incerta
Term
The neurons of __ have widespread reticular connections (function unknown).
Definition
Zona Incerta
Term
A crucial relay of the basal ganglia
Definition
Subthalamuc Nucleus
Term
Name 7 structures located in the hypothalamus
Definition
1. Mamillary Bodies
2. Tuber Cinereum
3. Infundibulum
4. Neurohypophysis
5. Optic Chiasm
6. Fornix
7. Several hypothalamic nuclei
Term
What separates the thalami?
Definition
3rd Ventricle
Term
A shallow groove on the ventricular surface just above the mammillothalamic tract
Definition
Hypothalamic Sulcus
Term
Separates the thalamus from the hypothalamus
Definition
Hypothalamic sulcus
Term
A major source of afferent fibers to the cortex, communicates with the cortex via thalmaic radiations
Definition
Thalamus
Term
Where particularly are the thalamic radiations?
Definition
regions of the lateral thalamus to the internal capsulle and then to cortex
Term
A prominent relay center to the cerebellum and the basal ganglia
Definition
Thalamus
Term
How many thalamic nuclei are there usually?
Definition
more than 30
Term
Thalamic nuclei can be classified as 1 of 3 major groups. Name those 3 groups
Definition
Anterior nuclear group
Medial nuclear group
Lateral nuclear group
Term
Includes both a dorsal and ventral group or tier, as well as the medial and lateral geniculate bodies
Definition
Lateral nuclear group
Term
The medial and lateral geniculate bodies are collectively known as what?
Definition
Metathalamus
Term
What divides the thalami?
Definition
Internal medullary lamina
Term
Name the 3 nuclei that are not contained within 1 of the 3 major groups.
Definition
Reticular
Midline
Intralaminar
Term
Depending on the kind of information relayed by the thalamus, several types of functional groups of nuclei are evident neuroanatomically. (3)
Definition
1. Relay Nuclei (External & Internal)
2. Diffuse Nuclei (Nonspecific)
3. Association Nuclei
Term
Which relay nuclei are found in the ventrolateral tier?
Definition
External Relay Nuclei
Term
Which relay nuclei are found in the anteroventral region?
Definition
Internal Relay Nuclei
Term
Have reciprocal connections with well defined cortical areas which have specific motor and sensory functions.
Definition
Relay Nuclei (external and internal)
Term
These nuclei relay information from the body and the external world to primary sensory cortical areas.
Definition
External Relay nuclei
Term
Receives input from the optic tracts and projects via geniculocalcarine tract to the primary visual cortex (area 17)
Definition
Lateral Geniculate Nuclei
Term
Name 4 external relay nuclei
Definition
1. Lateral Geniculate
2. Medial Geniculate
3. Ventral Posterolateral
4. Ventral Posteromedial
Term
Receives input from the brachium of hte inferior colliculus and projects to the primary auditory cortex (area 41 and 42)
Definition
Medial Geniculate Nuclei
Term
Receives input from the medial lemniscus and anterolateral system and projects to the primary sensory cortex (areas 1, 2, and 3) which contains the representation for the body and limbs
Definition
Ventral Posterolateral Nucleus (VPL)
Term
Receives input from the trigeminal lemniscus and projects to the primary sensory cortex (areas 1, 2, and 3) which contains the representation for the head
Definition
Ventral Posteromedial Nucleus (VPM)
Term
Receives information which has already undergone processing by one brain system and relay it to appropriate cortical regions.
Definition
Internal relay nuclei
Term
Name 3 internal nuclei
Definition
Anterior Nucleus (A)
Ventral Anterior Nucleus (VA)
Ventral Lateral Nucleus (VL)
Term
Receives input from the limbic system via the mammillothalamic tract and fornix, before relaying that information on to the cingulate gyrus (limbic cortex)
Definition
Anterior Nucleus (A)
Term
Receives input from the basal ganglia and cerebellum and relays it to the motor and premotor areas (areas 4 and 6) of the cortex
Definition
Ventral Anterior Nucleus (VA)
Term
Receives input from the basal ganglia and deep cerebellar nuclei (particularly the dentate nuclei) via the dentatorubrothalamic tract and relays it to the motor cortex areas 4 and 6
Definition
Ventral Lateral Nucleus (VL)
Term
Located predominantly along the midline adjacent to the 3rd ventricle and within the internal medullary lamina (known as intralaminar nuclei)
Definition
Diffuse Nuclei
Term
Have diffuse cortical interconnections (rather than specific afferent/efferent connections)
Definition
Diffuse Nuclei
Term
Receive afferents from the spinal cord, reticular formation, basal ganglia, and the cerebral cortex (from widespread areas within the cortex) and project to widespread areas of cortex
Definition
Diffuse Nuclei
Term
Name the diffuse nuclei that we need to know specifically
Definition
Centromedian Nucleus
Term
Located primarily within the doral tier of the thalamus, both anteriorly and posteriorly
Definition
Association Nuclei
Term
Nuclei of this functional group acts as relays between cortical areas, between brain (internal) systems, or between other thalamic nuclei and the cortex.
Definition
Association Nuclei
Term
There are reciprocal fiber connections between this type of nuclei and with association areas of the cerebral cortex.
Definition
Association Nuclei
Term
Name the Association nucleus that we need to know.
Definition
Dorsomedial Nucleus
Term
The nuclei of the __ cannot be assigned one particular function.
Definition
Thalamus
Term
Help integrate, correlate, and relay information (sensory, motor, consciousness, limbic, and visual systems)
Definition
Thalamic Nuclei
Term
The only peripheral sensory stimulus that is interpreted thalamically.
Definition
Pain
Term
The __ located within this region of the diencephalon also function in the mechanisms by which the brain focuses attention and is involved in conscious perception and interpretation of pain.
Definition
Nuclei
Term
How does the thalamus help the brain to focus attention?
Definition
by altering cortical receptivity
Term
A termination point for all sensory impulses
Definition
Thalamus
Term
The thalamus is a termination point for all sensory impulses, with one notable exception. What is the exception?
Definition
Olfactory signals
Term
A primary sensory integrator (not a simple relay station) that is integral to the maintenance and regulation of consciousness, alertness, and attention.
Definition
Thalamus
Term
Function via widespread influences on the cerebral cortex (primarily inhibitory)
Definition
Thalamic Nuclei
Term
The cause of this syndrome is most likely due to large infarcts int he blood supply to the thalamus (typically these affect the posterior cerebral artery)
Definition
Thalamic Syndrome
Term
With Thalamic Syndrome, what thalamic area is most frequently involved?
Definition
The ventral posterolateral nucleus(VPL)
Term
With this syndrome, the VPL is most frequently involved however generalized thalamic damage is present
Definition
Thalamic Syndrome
Term
Name 4 characterizations of thalamic syndrome
Definition
1. Complete hemianesthesia (contra)
2. Permanent loss of tactile localization and 2 pt discrimination
3. Limited recovery of sensation (temp, crude touch, and pain)
4. Nonspecific evocation of pain sensations (pain may be sensed in response to most tactile stimuli)
Term
This was a treatment of choice for severe psychiatric disorders between 1940 and 1960.
Definition
Prefrontal Lobotomy (Leukotomy)
Term
Where the reciprocal connections between the dorsomedial nucleus (DM) of the thalamus and the frontal lobe is interrupted.
Definition
Prefrontal Lobotomy
Term
Eliminates effects of most sensations and impairs learning and memory.
Definition
Leukotomy
Term
Only used as a last resort to treat sever chronic depression today because of the deleterious personality changes that occur after the procedure.
Definition
Leukotomy
Term
Surgical interruption of the connections between the basal ganglia and the cerebral cortex are sometimes used to treat what disease?
Definition
Parkinsons
Term
The surgical procedure to treat Parkinson's may cause decreases in what 2 things?
Definition
Rigidity
Tremor
Term
Are decreases in rigidity and tremors in parkinson's patients after surgery permanent?
Definition
No
Term
As long as they are limited, do surgically induced lesions impair sensations?
Definition
No
Term
With parkinson's patients, the location of the thalamic lesion site is one of the following sites: (3)
Definition
1. Centromedian Nucleus (CM)
2. Ventrolateral Nucleus (VL)
3. Ventral Anterior Nucleus (VA)
Term
Designed to interrupt misinformation flowing through there from the globus pallidus and substantia nigra which produces tremor
Definition
Thalamotomy
Term
Name 2 components of the epithalamus.
Definition
Habenula
Pineal Gland
Term
What will an injury to the subthalamic nucleus result in?
Definition
Extra involuntary movement
Term
The subthalamus is part of the diencephalon and is a pathway for what?
Definition
Basal Ganglia
Term
This nucleus deals with optic tracts?
Definition
Lateral Geniculate Nucleus
Term
In the midline as part of the internal medullary lamins.
Definition
Centromedian Nucleus
Term
Name 4 functions of the thalamus
Definition
1. Information processing
2. Mechanism of attention
3. Conscious perception of pain
4. Provides widespread influence on the cortex
Term
If you have cranial nerve and long tract fiber involvement, are you inside or outside of the brainstem?
Definition
Inside
Term
If you have cranial nerve involvement but not long tract fiber involvement, are you inside or outside of the brainstem?
Definition
Outside
Term
What is the major association nuclei that we need to know for this class?
Definition
Dorsomedial Nucleus
Term
What is the major diffuse nuclei that we need to know for this class?
Definition
CM - centeromedian nucleus
Term
Level of pain is not what it should be. Cause is unknown.
Definition
Thalamic Pain Syndrome
Term
Lesin to the thalamus
Definition
Thalamotomy
Term
-Brakes on behavior
-Planning and executing goal-directed behavior
-Working memory
-Lack of inhibition, initiative, drive
Definition
Prefrontal Cortex
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