Thalamus (from cortex, thalamus and hypothalamus)

Question 1

What may nuclei in the thalamus function as?

Answer 1

Either:

1. relay nuclei
2. diffuse projection nuclei

Question 2

What do relay nuclei generally process?

Answer 2

either sensory information resulting from a specific type of stimulus (eg. vision, hearing, somatic sensation) or input from a particular part of the motor system

Question 3

What do the relay nuclei do?

Answer 3

send axonal projections to a region of the cerebral cortex that is also anatomically
restricted and defined by the source of input it receives (eg. visual information from retina is
processed in LGN in thalamus and projects to the visual cortex

Question 4

What are diffuse projection nuclei perceived to be involved in? Describe them

Answer 4

Mechanisms that regulate the state of arousal of the brain

they have more widespread connections that the relay nuclei and they include projections to the other thalamic nuclei

Question 5

Describe the 6 groups of thalamic nuclei

Answer 5

Nuclei of the thalamus are anatomically divided into 6 groups, separated by a Y-shaped collection of
fibers termed the internal medullary lamina – lateral, medial and anterior nuclei are named by their
location relative to this lamina; the remaining groups are the intra-laminar, reticular and midline nuclei

Question 6

Afferent and efferent connections of the anterior (limbic) thalamic nuclei

Answer 6

1. receives input from the hypothalamus and sends projections to the cingulate gyrus - hypothalamus → anterior group → cingulate gyrus (awareness and emotional aspects of sensory processing)
2. The lateral dorsal nucleus is involved in emotional expression and receives signals from, and sends them to, the cingulate gyrus - Cingulate gyrus → dorsal lateral nucleus → cingulate gyrus
3. The medial dorsal nucleus is also involved in limbic processing, receiving input from the amygdala, hypothalamus and olfactory system and sending axons to the prefrontal cortex - Amygdala, hypothalamus, olfactory system →
   dorsal medial nucleus → prefrontal cortex

Question 7

Afferent and efferent connections of the motor thalamic nuclei

Answer 7

Basal ganglia (globus pallidus, substantia nigra)
and cerebellum → ventral lateral nucleus →
motor cortex, premotor cortex, supplementary
motor cortex

• Globus pallidus and cerebellum → ventral
  anterior nucleus → premotor cortex

Question 8

Afferent and efferent connections of the somatosensory thalamic nuclei

Answer 8

Spinothalamic tract and medial lemniscus of dorsal column-medial lemniscal
pathway → ventral posterior lateral (VPL) →
primary somatosensory cortex
- this is somatic sensation from the body

• Trigeminothalamic tract (from solitary tract and
  trigeminal nerve) → ventral posterior medial (VPM)
  → primary somatosensory cortex
• this is facial sensory information

Question 9

Afferent and efferent connections of the visual thalamic nuclei

Answer 9

Retina → lateral geniculate nucleus (LGN) → V1 visual cortex (via optic radiation)

- Superior colliculus and association cortex →  pulvinar →  secondary visual areas and association areas in
parietotemporal region (visual perception and eye movements, attention)

Question 10

Afferent and efferent connections of the auditory thalamic nuclei

Answer 10

Inferior colliculus → medial geniculate nucleus (MGN) → auditory cortex

Question 11

Nucleus for vision

Answer 11

LGN

Question 12

Nucleus for vestibular nerve

Answer 12

VPM

Question 13

Nucleus for auditory nerve

Answer 13

MGN

Question 14

Nuclei for somatosensation

Answer 14

VPL (body)

VPM (face)

Question 15

Nucleus for pain

Answer 15

VPL

Question 16

Nucleus for taste

Answer 16

VPM

Question 17

Nuclei recieving input from cerebellum

Answer 17

VL nucleus

Question 18

Nucleus recieving input from BG

Answer 18

VA nucleus