5.2 Thalamus & Hypothalamus Flashcards
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
fine lines of white matter going through the grey matter;
3rd ventricle:;
forebrain
what is the function of the thalamus?
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)
which nucleus of the thalamus extends all over the entire lateral thalamic surface (covering all the interior structures)
reticular nucleus
where does the specific nuclei connect to?
To primary cortical areas
where does the association nuclei connect to?
To the association cortex
where does the intralaminar nuclei connect to?
To all cortical areas
where does the reticular nuclei connect to?
Not connected to the cortex → only to other thalamic nuclei
where does the ventral lateral nuclei (VL) connect to?
Motor cortices (primary, premotor, supplementary)
where does the ventral posterolateral nuclei (VPL) connect to?
Somatosensory (body)
where does the ventral anterior (VA) nuclei connect to?
Motor cortices (primary, premotor, supplementary)
Where does the ventral posteromedial (VPM) nuclei connect to?
Somatosensory (head)
where does the lateral geniculate nuclei connect to?
Primary visual cortex
where does the medial geniculate nuclei connect to?
Primary auditory cortex
where does the anterior (A) nuclei connect to?
Cingulate (on median surface of brain)
Prefrontal (anterior to primary motor cortex including Broca’s area (producing speech))
where does the lateral dorsal (LD) nuclei connect to?
Cingulate (on median surface of brain)
Prefrontal (anterior to primary motor cortex including Broca’s area (producing speech))
Where does the dorsomedial nuclei (DM) connect to?
Cingulate (on median surface of brain)
Prefrontal (anterior to primary motor cortex including Broca’s area (producing speech))
Where does the lateral posterior (LP) connect to?
Parieto-temporo-occipital (posterior to primary somatosensory cortex including Wernicke’s area (comprehending language))
Prefrontal
Where does the Pulvinar (P) nuclei connect to?
Parieto-temporo-occipital (posterior to primary somatosensory cortex including Wernicke’s area (comprehending language))
Prefrontal
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
reticular and intralaminar thalamic
What is the function of the reticular activating system?
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
where does intralaminar nucleus projects to?
Projects axons to all areas of the cortex (diffuse projections)
where does reticular nuclei projects to?
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)
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
inferior and anterior;
3rd ventricle
what lies anterior to the hypothalamus?
Optic chiasm (where the optic nerves come together)
what lies inferior to the hypothalamus?
Pituitary gland (connected to the inferior aspect of the hypothalamus via the infundibulum/pituitary stalk)
how does the circadian rhythm work?
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
