Functional Neuroanatomy Unit 2

The thalamus is found (who has it) :

In all vertebrates

Explain what the thalamus is

Paired structure deep in the brain that processes routes and information to the cerebral cortex. An organized collection of processing stations, each connected to particular brain regions

The thalamus is located in the :

Diencephalon, near the center of the brain

The thalamus relays and processes:

sensory signals going to the cerebrum, motor signals coming from the cerebrum

The thalamus contains many:

specialized nuclei, with functional organization projecting to specific brain regions

How are the two thalami connected?

They are connected across the third ventricle, via interthalamic adhesion

The thalamus does more than just pass signals along. It helps:

select and modify info before reaching the cortex.

The thalamus relays/modifies information, and many axons carrying information between the thalamus and cortex travel through the _____

Internal capsule

The internal capsule is:

a dense bundle of white matter deep within each cerebral hemisphere. It contains axons travelling in both directions (ascending and descending fibers)

In the internal capsule, which way do the two types of fibers travel?

Ascending fibers: sensory info from thalamus to cortex. Descending fibers: motor info from cortex to thalamus, brain step, spinal chord

Label the parts of the internal capsule

Red is Anterior limb, between head of caudate nucleus medially and lentiform nucleus laterally. Blue is genu, connecting the two limbs. Yellow is posterior limb

What is the external medullary lamina?

A thin sheet of white matter that separates the main thalamic nuclei from the reticular nucleus, which is on the side. Beyond the thalamic reticular nucleus on that same lateral side is the internal capsule.

What is the internal medullary lamina?

Sheet of white matter that divides the thalamus internally. It separates the medial nuclear mass from the lateral nuclear mass

Describe the two types of fibers in the internal capsule, in what they’re called OTHER than ascending/descending

Thalamocortical fibers: Sensory info. Carry thalamic output to cortical areas. Corticothalamic: Cerebral cortex to the thalamus, allow cortex to influence thalamic processing.

What structure is after the internal capsule going outward from the thalamus?

basal ganglia

What is this?

The thalamus

Where do the thalamic nuclei project to?

All thalamic nuclei except the reticular nucleus project to the ipsilateral side of the cerebral cortex. So left thalamus projects to left cerebral cortex, right thalamus projects to right cerebral cortex. Reticular nucleus is the exception because its output goes to other thalamic nuclei, allowing it to regulate their activity

What part of the cerebral cortex receives thalamic input?

The entire cerebral cortex

Thalamic nuclei receive ______ fibers in a ______ fashion

corticofugal, basically reciprocal

Explain what is meant by this statement: “Thalamic nuclei receive corticofugal fibers in a basically reciprocal fashion”

Corticofugal here means corticothalamic. Corticofugal is a general term for traveling away from the cortex. This is saying that the cortical area receiving input from a thalamic nucleus sends projections back to that nucleus. This feedback allows the cortex to influence the information in thalamic relays

What are the three nuclear groups of the thalamus?

Anterior, Medial, and Ventral

Where is the anterior nuclear group located?

Dorsomedial surface of the thalamus at the rostral limit