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61 Cards in this Set

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What are the subdivisions of the diencephalon
Dorsal Thalamus
Ventral Thalamus,
Hypothalamus
Epithalamus,
Subthalamus

and Mammillary bodies -limbic
Where is the dorsal thalamus located?
At the lateral wall of the third ventricle
What are some key features of the dorsal thalamus?
The dorsal thalamus (called the thalamus) is the main bulk of the diencephalon.It has nuclei that provide links to the cortex. It has an external medullary lamina- a sheath that surrounds the dorsal thalamus. It has internal medullary lamina - subdivides in the center.
What are some of the key features of the ventral thalamus?
The ventral thalamus has 2 nuclei- reticular nuclei of the thalamus and the ventral lateral geniculate nucleus.
What are some of the key features of the hypothalamus?
The hypothalamus is a key controlling center of the ANS and endocrine system. It mediates endocrine control via connections to the hypophysis.
What is the primary arterial supply to the thalamus?
The PCA. The others that supply are off the circle of willis (ACA, internal carotid, Acomm,Pcomm) NOT MCA!!!!!
What is the thalamic neuronal circuit?
afferent input travels to thalamic relay neurons to the cerebral cortex. Some reciprical connection exists from the cortex to the thalamic relay neurons. There are then thalamic interneurons that receive afferent input and then project it to the thalamic neurons.
The thalamus receives all sensory input except that coming from
Olfaction
Besides integrating/ relaying sensory information to association cortex and integrating motor information, what else does the thalamus do?
1) Relays emotional and affective info to the cortex
2) Part of the Papez circuit of the limbic system
3) Participates in control of alertness, arousal, and sleep
What are the groups of specific relay nuclei in the thalamus?
Anterior nuclear group, lateral-ventral tier, lateral dorsal tier, medial group
What makes up the lateral ventral tier?
The lateral ventral tier is a group of specific relay nuclei in the thalamus. It is made up of the ventral anterior (VA), ventral lateral (VL), ventral posterior lateral (VPL), ventral posterior medial (VPM), Lateral geniculate (LGN), Medial geniculate (MGN).
What makes up the lateral dorsal tier?
The lateral dorsal tier is a group of specific relay nuclei in the thalamus. It is made of the lateral dorsal (LD), Lateral posterior (LP), and pulvinar (Pul)
What makes up the medial group?
The medial group is a group of specific relay nuclei. It is composed of the medial dorsal group.
What is the afferent input of the anterior nuclear group? Where are its projection sites to? What are its functions?
The afferent input of the anterior nuclear group is the mammillary body. The projection sites were the cingulate gyrus. This serves limbic function.
What is the afferent input of the ventral anterior nucleus? Where does it project to? What are its functions?
The afferent input of the ventral lateral nucleus is the globus pallidus. It projects to premotor cortex (area 6) and serves motor function.
What is the afferent input of the ventral lateral nucleus? Where does it project to? What are its functions?
The afferent input of the ventral lateral nucleus is the dentate nucleus of the cerebellum. It projects to the motor and premotor areas (4, 6) and has motor functions.
What is the afferent input of the ventral posterior lateral? Where does it project to? What are its functions?
Afferent input of the VPL is the dorsal column medial lemniscus and spinothalamic tract. They project to somatosensory cortex (3,1,2). FUnction is somatic sensation (Body)
What is the VPM? Where is its afferent input from? Where does it project to? What is the function?
The ventral posterior medial is a specific relay nuclei of the thalamus, getting its input from the sensory nuclei of trigeminal nerve and projecting to somatosensory cortex (areas 3,1,2). Somatic sensation (face)
What is the lateral geniculate nucleus? where does it get its afferent input from? where does it project to? What is its function?
The lateral geniculate nucleus gets its input from the retinal ganglion cells. It is a specific relay nuclei of the thalamus. It functions in vision and its projections go to the primary visual cortex (area 17).
What is the medial geniculate nucleus? Where does it get its afferent input from? Where does it project to? What does it function in?
The MGN is a specific thalamic relay nuclei that gets its afferent input from the inferior colliculus and projects to the primary auditory cortex (areas 41,42). It functions in audition.
What is the lateral dorsal nucleus? Where does it get its afferent input from? Where does it project to? What is its function?
The Lateral Dorsal nucleus is a specific relay nucleus of the thalamus, getting its input from the cingulate gyrus, projecting to the cingulate gyrus, and functioning in emotional expression
What is the lateral posterior nucleus ? Where are its afferents? Where does it project to? what are its functions?
The lateral posterior nucleus is a specific relay nucleus of the thalamus, getting its input from the parietal cortex, projecting to the parietal cortex and functioning on sensory integration.
What is the pulvinar nucleus ? Where are its afferents? Where does it project to? what are its functions?
The pulvinar nucleus is a specific relay nucleus of the thalamus, taking information from the superior colliculus and parietoocipital lobe, projecting to parietooccipital lobe, and focusing on integrating sensory information.
What is the MD nucleus? Where are its afferents? Where does it project to? what are its functions?
The medial dorsal nucleus is a specific relay nucleus of the thalamus, taking its input from the amygdala, hypothalamus, and olfactory; projects to prefrontal cortex, and functions in limbic system.
What is the midline nuclei? Where are its afferents? Where does it project to? what are its functions?
The midline nuclei is a diffuse projection nuclei. It takes its afferent input from reticular formation and hypothalamus. It projects to the basal forebrain and fucntions in limbic system.
What is the intralaminar nuclei? Where are its afferents? Where does it project to? what are its functions?
Intralaminar nuclei are diffuse projection nuclei including CM (centromedian), CL (centrolateral) and PF (parafasciularis). They play a role in pain/sleep wakefulness. They take input from the reticular formation, spinothalamic tract, globus pallidus, and cortical areas; they project to basal ganglia and cortex.
What is the reticular nucleus? Where does it get its afferent input from? Where does it project to? What is its function?
The reticular nucleus is a diffuse projection nucleus that takes its afferent input from the cortex, thalamus, and brainstem and projects to thalamic nuclei. This functions in modulating thalamic activity.
What are some salient features of the diffuse projections nuclei?
They are intralaminar (within the internal medullary lamina), midline, all have their afferents from the reticular formation
Why is the reticular nucleus unique?
It modulates the thalamus (selfmodulation)
What are the functions of the nonspecific thalamic system?
Control neuronal excitability and maintain wakefulness, sleep, arousal, and alertness.
What is the nonspecific thalamic system's function
To control the level of excitability of neurons over wide areas of the cortex and to maintain wakefulness, sleep, arousal alertness.
How is the nonspecific thalamic system activated?
Through repetitive low frequency stimulation
How do the connections in the nonspecific thalamic nuclei work?
There are reciprocal connections with specific thalamic nuclei. There are also connections between the different nonspecific systems.
Describe thalamic syndrome cause.
Cause: vascular lesion or tumor damages lateral group of thalamic nuc (VPL)
Describe what happens to a patient that gets thalamic syndrome.
• Transitory contralateral hemianalgesia is the first sign.
This is followed by painful sensations appear with noxious stimuli.
Then pain is provoked by pressure, touch and vibration (allodynea)
Later, state of spontaneous, constant, or paroxysmal pain is evoked on affected side (contralateral to lesion) without any stimuli (dysesthesia)
• Threshold for pain, temperature and tactile sensation = raised on affected side (harder to get response) BUT pain has a strong emotional overtone to it when it is evoked
What is the nonspecific thalamic system's function
To control the level of excitability of neurons over wide areas of the cortex and to maintain wakefulness, sleep, arousal alertness.
How is the nonspecific thalamic system activated?
Through repetitive low frequency stimulation
How do the connections in the nonspecific thalamic nuclei work?
There are reciprocal connections with specific thalamic nuclei. There are also connections between the different nonspecific systems.
Describe thalamic syndrome cause.
Cause: vascular lesion or tumor damages lateral group of thalamic nuc (VPL)
Describe what happens to a patient that gets thalamic syndrome.
• Transitory contralateral hemianalgesia is the first sign.
This is followed by painful sensations appear with noxious stimuli.
Then pain is provoked by pressure, touch and vibration (allodynea)
Later, state of spontaneous, constant, or paroxysmal pain is evoked on affected side (contralateral to lesion) without any stimuli (dysesthesia)
• Threshold for pain, temperature and tactile sensation = raised on affected side (harder to get response) BUT pain has a strong emotional overtone to it when it is evoked
What are the major afferents & efferents to the cerebral cortex?
Afferents: thalamus
Efferents: thalamus, BG, BS, SC.
-notice no cerebellum!
What are the major vessels that supply the cortex with blood
• ACA, MCA, PCA, Acom (maintains perfusion during thrombosis of ACA) & Pcomm
• NOT the internal carotids directly
What are the divisions of the cerebral cortex?
Archicortex, neocortex, paleocortex
How many layers are in the archicortex?
3
What are the components of the archicortex?
Hippocampus, dentate gyrus
What is the function of the paleocortex?
Olfaction
Which layer of the cortex makes up the bulk of the cortex? What are its layers?
The neocortex

 I: Molecular - cell sparce
 II: External granular - granular cells, corticocortical projections
 III: External Pyramidal – small and medium size pyramidal cells
 IV: Internal Granular – granular cells
 V: Internal Pyramidal - Betz cells (medium to lg pyramidal cells)
 VI: Multiform – mix of fusiform, pyramidal and granular
What is the function of pyramidal cells?
Nonpyramidal?
Pyramidal- glutamatergic axons project down (lots of collaterals) and go to other areas of the brain.

Nonpyramidal are primarily interneurons that can release several neurotransmitters.
What is the functional unit of the cerebral cortex called? What are its features?
A column. 300 -500 nm wide, these connect all 6 layers together vertically, and within the column, cells have similar function. Columns connect to each other within the same hemisphere and cross hemispheres. Columns combine to form modules
What are the physical differences between the motor and sensory cortex?
Sensory cortex has a more layered appearance and a huge layer 4 to accept thalamic input.

The motor cortex is thicker, has less defined areas, and has Betz cells in layer V.
What are the corresponding cortical structures and major thalamic connections of Broadmans area 3,1,2
• 3, 1, 2 - Primary sensory on the post central gyrus
o Spinothalamic tract, CN V, dorsal column -> VPL, VPM -> 3, 1, 2
o Contralateral inputs
What are the corresponding cortical structures and major thalamic connections of Broadman's area 4,6?
• 4, 6 - Primary motor, premotor on precentral gyrus
o GP, dentate nucleus -> VA, VL ->4, 6
o Contralateral control
What are the corresponding cortical structures and major thalamic connections of Broadman's area 17
Cuneus, lingual for Primary visual cortex
o Retina ->LGN-> 17
o Everything is backwards and upside down
What are the corresponding cortical structures and major thalamic connections of Broadman's area 41, 42
• 41, 42 - Primary auditory, Heshel's Gyrus
o Inf. Colliculi -> MGN -> 41, 42
 Lots of bilateral innervation so rarely does cortical damage result in deafness
o Left 21, 22 = Wernicke’s area
What are the corresponding cortical structures and major thalamic connections of the broadmans area 44, 45?
• 44, 45 - Primary Speech, Broca’s area
o Left dominance in 95% of people
What are the corresponding cortical structures and major thalamic connections of the prefrontal cortex?
• Prefrontal cortex – executive fxn: foresight, decision making; limbic function
o Olfactory, hypothalamic, amygdala -> MD -> prefrontal
What are the corresponding cortical structures and major thalamic connections of the cingulate?
• Cingulate - emotion
o Mammillary bodies-> Anterior nucleus groups -> cingulate
o cingulate -> LD-> cingulate
What are the general functions of the Cerebral Cortex?
• Perception of special senses
• Voluntary movement – planning & execution
• Emotion & Behavior
• Mental fxning – judgment and foresight
• Memory (all over)
What are the most common reasons for cortical lesions?
• Vascular hemorrhage
• Vascular Thrombosis
• Tumor – glial origin (MC)
How would these lesions present
• Lesion of Primary Motor Cortex
• Lesion of Primary Sensory Cortex
• Lesion of Primary Visual Cortex
• Lesion of Primary Motor Cortex - contralateral paralysis
• Lesion of Primary Sensory Cortex – contralateral loss of somatic sensation
• Lesion of Primary Visual Cortex – contralateral hemianopia
How would these lesions present

• Lesion of Supramarginal Gyrus

Lesion of Angular Gyrus

Lesion of Brocas Area on dominate hemisphere
• Lesion of Supramarginal Gyrus – astereognosis – loss of ability to perceive the form of an object by using the sense of touch
• Lesion of Angular Gyrus – alexia and agraphia – loss of ability to read, loss of ability to write (agraphia = specific loss of the ability to produce written language even when other manual motor abilities are intact)
o Alexia without agraphia = localizes to corpus collosum (occipital spelenium)
• Lesion of Broca’s area on dominate hemisphere – motor aphasia/non-fluent aphasia