6 Thalamus Flashcards by Jake Evans

Global card (5 things): What are the basic functions of the thalamus?

Sleep/vigilance/attention
Sensory & motor “gate” for what reaches awareness
—Not for smell & some “emotional” pain/visceral senses
—ONLY gate from cerebellum & basal ganglia to cortex
Level and content of consciousness

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T/F Thalamus is the ONLY gate from cerebellum & basal ganglia to cortex?

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Thalamus is a sensory/motor gate for everything except what?

-smell & some “emotional” pain/visceral senses

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Pg. 2 of notes has an intense anatomy figure of the thalamus, so if you’re using these cards in place of studying the lecture notes…

Go look at it real quick, then come back :)

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Thalamic motor nuclei are clustered directionally where?

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Thalamic sensory nuclei are clustered directionally where?

Posterior

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What marks the division between medial and lateral thalamic nuclei?

Internal Medullary Lamina (separates MD nucleus from LD nucleus)

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What is the largest intralaminar thalamic nucleus?

centromedians (largest intralaminar nucleus in humans)

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What are the midline thalamic nuclei?

Paraventricular, rhomboid, reuniens

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T/F thalamus is involved in level and content of consciousness?

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T/F “Specific” nuclei are typically not reciprocally connected w/ cortex?

F. They are.

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T/F “Specific” nuclei maintain spatial organization of senses?

True

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What are the sensory thalamic nuclei?

MGN, LGN, VPM, VPL

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What are the motor thalamic nuclei?

VA, VL

ventral anterior, ventral lateral

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What are the association specific nuclei?

MD, P

mediodorsal, pulvinar

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what are the limbic specific nuclei?

Anterior, lateral dorsal (sometimes MD is also included)

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Non-specific thalamic are different than the “specific” nuclei we already covered. Since we already covered “specific” nuclei, name the 4 differences that define non-specific nuclei?

Diffuse/multimodal
NOT-reciprocal w/ cortex, but reciprocal w/ basal ganglia
Sensory info NOT spatially organized
Strong input from MIDBRAIN reticular formation

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What are the 2 categories of non-specific thalamic nuclei?

Intralaminar, midline

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VPM is for what? Reciprocally connected w/ what?

mnemonic: For your “Mug” (face)
All sensory from face thru trigeminal lemniscus
Reciprocally connected w/ postcentral gyrus

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VPMpc is the end of what pathway? And is reciprocally connected w/ what?

Taste buds–> NTS–> Pontine/Mesencephalic taste relay–>VPMpc (parvocellular)
-reciprocal connection: anterior insula

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VPL is for what? Reciprocally connected w/ what?

mnemonic: For you “Limbs”
Spinothalamic tract (which also has projections outside VPL) & medial lemniscus
Reciprocal connection: Postcentral gyrus

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VPI is for what?

Transmits vestibular info to inferior parietal lobule

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LGN has how many layers?

MGN is for what? Reciprocally connected w/ what?

Mnemonic: M is for “music”
auditory input from inferior colliculus
reciprocal connection: primary auditory cortex (Heschl’s gyrus of temporal lobe)

VA is for what?

- Mnemonic: A is for "bAsAl gAngliA" - Medial portion: Receives inhibitory input from ipsilateral basal ganglia for eye, head, neck movements - Lateral portion: Receives input from globus pallidus for trunk and limb regions

VL is for what?

- Mnemonic: L is for "cerebeLLum" | - Receives crossed input from cerebellum (via deep nuclei, the dentate-rubro-thalamic path)

VA is Reciprocally connected w/ what?

-Reciprocal connection: Premotor cortex, frontal eye fields, cingulate & parietal cortices

VL is Reciprocally connected w/ what?

-Reciprocal connection: primary motor cortex (precentral gyrus) AND sends axons to premotor, parietal, and superior temporal cortices

Basal ganglia effect is ipsi or contralaterally?

contralateral

Cerebellar effect is ipsi or contralaterally?

ipsilateral

MD has connections with what?

Connections w/ frontal & orbital cortices.

Lesions of MD result in?

apathy, memory changes, difficulty switching tasks (perseveration)

Pulvinar receives input from where?

-Input from retina, sup. colliculus, and (indirectly spinothalmic tract)

Pulvinar has What reciprocal connections?

-Reciprocal connections with 2nd-order sensory & multimodal association cortices in parietal, temporal, occipital lobes AND cingulate & frontal cortices

Lesions of pulvinar produce what problems?

language processing, visual perception, pain perception

T/F thalamic association nuclei receive reciprocal connections with cortex?

What is the purpose of thalamic association nuclei?

Integration of dif. types of sensory stimuli

T/F Sensory systems are the main source of activation in thalamic association nuclei?

F. The cortex is.

Anterior nuc. of thalamus is for? Reciprocally connected w/?

- Receives info from parahippocampal region (thru fornix) and mammillary bodies (thru mammillothalamic tract) - Reciprocal connection: cingulate gyrus

t/f anterior nuc. of thalamus has the densest serotonergic input from midbrain?

F. Cholinergic.

Laterodorsal thalamic nuc. is for?

``` Parahippocampal info (thru fornix) -Reciprocal connection: Retrosplenial cortex ```

Korsakoff's syndrome (alcoholic amnesia) produces changes where?

- Mammillary bodies | - anterior group of thalamic nuclei

spatial and context-dependent memory depends on what kind of neural system?

distributed neural system

Non-specific thalamic nuclei receive input from where?

- locus ceruleus - dorsal raphe - Periaqueductal gray - mesencephalon/pons input (reticular activating system, ACh) is more significant in intralaminar group

Midline group of nonspecific thal. nuclei send output where?

cortex, striatum (for general arousal)

Intralaminar group of nonspecific thal. nuclei send output where?

Striatum (for attention to motor tasks)

Lesions of centromedian nuc. lead to?

unilateral motor neglect (loss of attention function, since recall this is an intralaminar thalamic nucleus)

What 2 types of thalamic neurons exist?

- thalamocortical projection | - inhibitory interneuron (to other thalamic areas)

What 2 sub-types of thalamocortical projections exist?

- Restricted | - Widespread

How is global synchrony produced in the brain?

-"Restricted" projection sends signal, creating localized synchronous activity w/ cortex. Cortex signals back, which activates a "widespread" projection to cortex. Now global synchrony occurs.

When thalamic reticular nucleus is on tonically, what happens to sensory info?

- Awake state | - Thalamic signal to cortex mirrors sensory info

When thalamic reticular nucleus is on phasically, what happens to sensory info?

- Sleep state | - Thalamic signal to cortex IGNORES sensory info

Thalamic reticular nucleus (TRN) consists of what type of neurons?

GABA (innervate the WHOLE thalamus and all fibers communicating w/ cortex!)

Too much GABA (from a drug) would cause what?

TRN interference w/ sleep/wake awareness of stimuli (many sedatives are GABA agonists)

What SENSORY effects do thalamic lesions have in common?

hemianesthesia- VPM/VPL hemihypoacusis-MGN hemianopsia/quadrantopsia-LGN (contralateral)

What MOTOR effects do thalamic lesions have in common?

motor neglect, speech difficulties, abnormal movements if VA, VL or intralaminar nuclei

What OTHER effects do thalamic lesions have in common?

- memory impairments, - aphasia (pulvinar) - altered pain perception (Dejerine-Roussy syndrome=hyperesthesia to pain and anesthesia to discriminative touch, both on same side) - Awareness (coma or drowsy)