Neuro Anatomy: Lecture 13 Thalamus

thalamus

relays information in and out of the brain

regulates limbic system

plays role in consciousness

Thalamus is located

above the midbrain

Caudal boundary of thalamus

behind mamillary body to posterior commissure

mamillary bodies

relay stations for formation of memories

memories are influence by

the limbic system (emotion)

rostral boundary

anterior commissure along lamina terminalis to optic chiasm

anterior commisure

connects the temporal lobes

lamina terminalis

thin sheet that joins with the tuber cinereum to form pituitary stalk

medial to thalamus is

third ventricle

massa intermedia of thalamus

Connects right and left half of thalamus in the 3rd ventricle

lateral to thalamus is

internal capsule

Parts if Thalamus/dienchephalon

1. Dorsal Thalamus

2. Hypothalamus

Dorsal thalamus and hypothalamus are separated by

hypothalamic sulcus (part of 3rd ventricle)

he thalamus is a collection of

nuclei divided by white matter tracts

internal medullary laminar

white matter tract separating the nuclei in thalamus

Three major regions

Anterior

Medial

Ventral Posterior Lateral

Thalamic nuclei classificaiton by behavior

Principle

intralmainar

midline

reticular

Principle thalamic nuclei include

relay

associational

relay nuclei

relays information from a specific tract to a specific area of cortex

associational nuclei

receives info from diffuse areas and sends to diffuse areas of the brain

Principle relay nuclei include

VPL, VPM, LGN, MGN, VL, VA, anterior

VPL

relay principle nucleus

relays info from medial lemniscus (specific tract) to area 312 (specific part of brain)

VPM

conveys sensory information from the head

Trigeminal nerve --> trigeminal nucleus --> axon leaves and crosses --> ventral trigeminothalamic tract --> VPM --> area 43

lateral geniculate nucleus

principle relay nucleus

relays from optic nerve to visual cortex

Medial geniculate nucleus

principle relay nucleus

relays from brachium inferior colliculus to Transvers temporal Gyri of Heschl (areas 41,42)

Ventral anterior (VA)

principle relay nucleus

modulation of motor activity

cerebellum and basal ganglia

(denate nucleus, cerebellum, globulus pallidus, basal ganglia, Pars reticulata, substastia nigra)

goes to motor cortex and frontal lobe

VL projects to

internal capsule

area 4

precentral gyrus, frontal lobe

VA projects to

internal capsule

area 6

premotor cortex, supplementary motor cortex, frontal lobe; (Motor)

Anterior nucleus

principle relay

encoding of memories

mammillary bodies t--> anterior --> cingulate gyrus (above corpus callosum)

association nuclei include

lateral posterior, Pulvinar, dorsomedial

Two major areas of association cortex

prefrontal (rostral to motor areas of frontal lobe)

parietal-occipital-temporal (surrounding primary sensory areas)

Function of associational nuclei

higher order integration

Lateral posterior nucleus and pulvinar

project to parietal occipital temporal

visual processing

dorsomedial nucleus

projects to pre-frontal cortex

uses memory and emotion ot help make decisions

Inralaminar nuclei

in white matter tract

receive information from reticular activating system

projecto to widesprea areas of cortex

"wake up nuclei"

Inralaminar nuclei include

centromedian

parafasicular

reticular nuclei

inhibit other thalamic nuclei

Inhibiting stimuli from waking you

outside if thalamus

sheet of tissue

midline nuclei

Play a role in "Flexible cognition" and stress regulation

small dot like - near dorsomedian

Midline nuclei act as a hub between your strategic/emotional brain and hippocampus (long-term memory/place navigation), allowing you to use past knowledge to navigate a new area without getting lost.