5.2 Thalamus & Hypothalamus

Question 1

The thalamus is a collection of several small functionally distinct nuclei (separated by ______________) divided into 2 by the _______________
• Nuclei in each part of the thalamus have ipsilateral connections with the ___________, and also interconnections between themselves

Answer 1

fine lines of white matter going through the grey matter;

3rd ventricle:;

forebrain

Question 2

what is the function of the thalamus?

Answer 2

Serves as a relay centre (carries information in both directions between the cerebral cortex and the rest of the CNS) which integrates information (all functional systems in the CNS have a thalamic nucleus as a relay centre → except olfactory system)

Question 3

which nucleus of the thalamus extends all over the entire lateral thalamic surface (covering all the interior structures)

Answer 3

reticular nucleus

Question 4

where does the specific nuclei connect to?

Answer 4

To primary cortical areas

Question 5

where does the association nuclei connect to?

Answer 5

To the association cortex

Question 6

where does the intralaminar nuclei connect to?

Answer 6

To all cortical areas

Question 7

where does the reticular nuclei connect to?

Answer 7

Not connected to the cortex → only to other thalamic nuclei

Question 8

where does the ventral lateral nuclei (VL) connect to?

Answer 8

Motor cortices (primary, premotor, supplementary)

Question 9

where does the ventral posterolateral nuclei (VPL) connect to?

Answer 9

Somatosensory (body)

Question 10

where does the ventral anterior (VA) nuclei connect to?

Answer 10

Motor cortices (primary, premotor, supplementary)

Question 11

Where does the ventral posteromedial (VPM) nuclei connect to?

Answer 11

Somatosensory (head)

Question 12

where does the lateral geniculate nuclei connect to?

Answer 12

Primary visual cortex

Question 13

where does the medial geniculate nuclei connect to?

Answer 13

Primary auditory cortex

Question 14

where does the anterior (A) nuclei connect to?

Answer 14

Cingulate (on median surface of brain)

Prefrontal (anterior to primary motor cortex including Broca’s area (producing speech))

Question 15

where does the lateral dorsal (LD) nuclei connect to?

Answer 15

Cingulate (on median surface of brain)

Prefrontal (anterior to primary motor cortex including Broca’s area (producing speech))

Question 16

Where does the dorsomedial nuclei (DM) connect to?

Answer 16

Cingulate (on median surface of brain)

Prefrontal (anterior to primary motor cortex including Broca’s area (producing speech))

Question 17

Where does the lateral posterior (LP) connect to?

Answer 17

Parieto-temporo-occipital (posterior to primary somatosensory cortex including Wernicke’s area (comprehending language))
Prefrontal

Question 18

Where does the Pulvinar (P) nuclei connect to?

Answer 18

Parieto-temporo-occipital (posterior to primary somatosensory cortex including Wernicke’s area (comprehending language))
Prefrontal

Question 19

The remaining thalamic nuclei are associated with the reticular activating system (receives input from the brainstem reticular formation):
• Reticular formation: core of grey matter passing through the brainstem containing many sensory inputs of various modalities → projects up to the ___________ and _____________ nuclei → all cortical areas

Answer 19

reticular and intralaminar thalamic

Question 20

What is the function of the reticular activating system?

Answer 20

important in maintaining awareness and control of the level of consciousness (damage can cause unconsciousness/coma)
o During daytime: amount of information travelling through reticular formation is high → allows us to stay awake and aware
o During sleep: amount of information travelling is much less → less aware

Question 21

where does intralaminar nucleus projects to?

Answer 21

Projects axons to all areas of the cortex (diffuse projections)

Question 22

where does reticular nuclei projects to?

Answer 22

No direct projections to the cortical areas; projects to other thalamic nuclei (regulates flow of information going through the other thalamic nuclei to the cortex)

Question 23

The hypothalamus lies __________________ to the thalamus and possesses several landmarks around its lower edge:
• Divided into 2 by the ________________, and separated into individual small nuclei with separate functions by fine lines of white matter like the thalamus

Answer 23

inferior and anterior;

3rd ventricle

Question 24

what lies anterior to the hypothalamus?

Answer 24

Optic chiasm (where the optic nerves come together)

Question 25

what lies inferior to the hypothalamus?

Answer 25

Pituitary gland (connected to the inferior aspect of the hypothalamus via the infundibulum/pituitary stalk)

Question 26

how does the circadian rhythm work?

Answer 26

Retina → suprachiasmatic nucleus in hypothalamus → projects widely to control various bodily functions (e.g. sleep-wake pattern, blood pressure, breathing, cardiovascular function) → synchronising them to daylight length