Neuro Diencephalon: Thalamus Ssom Keifer

Front 1

Thalamus
(considered to be ")

Back 1

"gateway to cerebral cortex"
b/c most sensory and motor info relayed b4 to cortex
Thus major feature is *thalamocortical projections*

Front 2

4 major thalamic nuclear groups

Back 2

Anterior Group
Lateral Complex
Ventral Complex
Medial Group

Front 3

the medial and lateral groups are divided by a band of myelinated fibers called _

Back 3

internal medullary lamina

Front 4

Thalamus
Anterior Group
(subdivisions)

Back 4

none

Front 5

Thalamus
Lateral Complex
(subdiv)

Back 5

lateral dorsal (LD)
lateral posterior (LP)
pulvinar

Front 6

Thalamus
Ventral Complex
(subdiv)

Back 6

ventral anterior (VA)
ventral lateral (VL):
-pars oralis (VLo)
-pars caudalis (VLc)
ventral posterior (VP):
-ventral posterolateral (VPL)
-pars oralis (VPLo)
-pars caudalis (VPLc)
-ventral posteromedial (VPM)
lateral geniculate nucleus (LGN)
medial geniculate nucleus (MGN)

Front 7

Thalamus
Medial Group
(subdiv)

Back 7

mediodorsal nucleus (MD)

Front 8

Major connections of thalamic nuclei
Anterior Nuclear Group
(receives input from)

Back 8

receives input from the mammillary bodies via the mammillothalamic tract and the hippocampus via fornix

Front 9

Major connections of thalamic nuclei
Anterior Nuclear Group
(projects to)

Back 9

cingulate gyrus via anterior limb of IC

Front 10

Major connections of thalamic nuclei
Anterior Nuclear Group
(function)

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limbic functions
memory

Front 11

Major connections of thalamic nuclei
Lateral Complex
(LD)

Back 11

receives input from hippocampus and projects to posterior parts of cingulate gyrus and parietal cortex

Front 12

Major connections of thalamic nuclei
Lateral Complex
(LP)

Back 12

reciprocally connected with *somatosensory association cortex*, particularly with Area 5 of superior parietal lobule

Front 13

Major connections of thalamic nuclei
Lateral Complex
Pulvinar

Back 13

receives input from superior colliculus
projects to parietal, temporal and occipital lobes
particularly cortical visual areas 18 and 19, this link comprises an extrageniculate visual pathway separate from main visual pathway

Front 14

Major connections of thalamic nuclei
Ventral Complex
VA

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receives input from globus pallidus and substantia nigra pars reticulata and projects to extensive areas of the prefrontal cortex
involved in motor function

Front 15

Major connections of thalamic nuclei
Ventral Complex
VLo

Back 15

input from the globus pallidus and projects to regions of premotor cortex posterior to the VA input (Area 6)
involved in motor function

Front 16

Major connections of thalamic nuclei
Ventral Complex
VLc and VPLo

Back 16

receives input from the cerebellum and projects to primary motor cortex (Area 4)

Front 17

Major connections of thalamic nuclei
Ventral Complex
VPLc and VPM

Back 17

VPLc receives somatosensory info from the medial lemniscus and the spinothalamic tract
VPM receives input from the trigeminothalamic tract
VPLc = Limb
VPM = "mouth"
both nuclei project to primary somatosensory cortex, this is a major pathway for appreciation of somatic sensations

Front 18

Major connections of thalamic nuclei
Ventral Complex
LGN

Back 18

receives crossed and uncrossed input from the retina via optic tract and projects to the primary visual cortex (Area 17)
it is part of the main visual pathway

Front 19

Major connections of thalamic nuclei
Ventral Complex
MGN

Back 19

receives input from the inferior colliculus and projects to the primary auditory cortex (Area 41)
it is part of the main auditory pathway

Front 20

Major connections of thalamic nuclei
Medial Group
MD
(4 inputs, output, function)

Back 20

receives input from other thalamic nuclei, the limbic system via the amygdala, the prefrontal cortex, and the substantia nigra
it projects to the prefrontal cortex
functions in aspects of affective behavior and memory
MD is consistently affected in Korsakoff's syndrome, sectioning the connections b/w this thalamic nucleus and the prefrontal cortex occurred during prefrontal lobotomies

Front 21

Thalamic lesions

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often not confined to specific nuclei
thalamus bordered by internal capsule so usually both involved

Front 22

Thalamus
(blood supply)

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PCA

Front 23

Thalamic syndrome

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may be cerebellar-like signs if VA and VL involved
vary with location but often:
impairment of Propriocept, sensations of touch, temp, and pain on cotralat
often *exaggerated* sensation
emotional instability like spontan laugh or cry
*spontaneous PAIN (hyperalgesia)

Front 24

Thalamic syndrome
spontaneous pain (hyperalgesia)
This is of _ origin (ie in absence of real stimuli) and often involves _ and _

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central origin
VPM and VPLc

Front 25

Hallmark of thalamic damage

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spontaneous Pain (hyperalgesia)

Front 26

Hypothalamic nuclei

Back 26

They exist

Front 27

Connections of Hypothalamus
Major inputs

Back 27

primarily limbic

Front 28

Connections of Hypothalamus
medial forebrain bundle

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cells of origin arise mainly from the septal and olfactory areas, it relays info related to arousal, emotion and smell
(small in humans)

Front 29

Connections of Hypothalamus
stria terminalis

Back 29

origin from amygdala,
this fiber bundle arches over the thalamus along the medial side of the caudate to terminate in hypothalamus
the inputs are related to smell and emotion

Front 30

Connections of Hypothalamus
fornix

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originates from the hippocampus and terminates in mammillary body

Front 31

Connections of Hypothalamus
Major inputs
(name)

Back 31

medial forebrain bundle
stria terminalis
fornix
brainstem
cortex

Front 32

Connections of Hypothalamus
Major outputs
(name)

Back 32

mammillotegmental tract
mammillothalamic tract

Front 33

Connections of Hypothalamus
mammillotegmental tract

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projects to the reticular formation of the midbrain and pons

Front 34

Connections of Hypothalamus
mammillothalamic tract

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projects to the anterior nucleus of the thalamus thereby providing a route for hypothalamic information to go to the cortex