Hypothalamus/Thalamus Flashcards
What region is the supraoptic nucleus found in?
Supraoptic region of the hypothalamus
More lateral - just above the optic chiasm
What is the role of the supraoptic nucleus?
Releases: oxytocin, ADH
Where is the suprachiasmatic nucleus found?
Supraoptic region of the hypothalamus
More medial, just above the optic chiasm
What are the input pathways to the suprachiasmatic nucleus?
Melanopsin containing ganglion cells in retina –> SCN
This is a different cell population than the rods and cones
Describe the outflow pathway from the suprachiasmatic nucleus and the physiolocial role this plays.
SCN –> paraventricular nucleus (inhibitory)
PVN –> lateral cell column (excitatory) –> superior cervical ganglion –> pineal gland (releases melatonin)
Light stimulation of the SCN inhibits the sympathetic pathway that stimulates melatonin secretion (i.e. light inhibits melatonin production)
Where is the paraventricular nucleus found?
In the supraoptic region of the hypothalamus
What do paraventricular nucleus cells secrete and what are its physiological roles?
Secretes oxytocin and ADH
Also secretes CRH to the adenohypophysis, ultimately leading to cortisol release from the adrenal glands
What are the three nuclei of the tuberal region of the hypothalamus?
Arcuate
Ventromedial
Lateral area (parvocellular region)
What are the three nuclei of the supraoptic region of the hypothalamus?
Paraventricular
Supraoptic
Suprachiasmatic
What two nuclei make up the magnocellular region of the tuberal region of the hypothalamus?
Medial portion of the tuberal region:
Arcuate nucleus
Ventromedial nucleus
What does the arcuate nucleus do?
Releases releasing hormones into the portal system:
TRH
CRH
GnRH
GHRH
Somatostatin
What does the ventromedial nucleus of the hypothalamus do?
“Satiety center”
Stimulation –> satiety; lesion –> hyperphagia, hypothalamic rage
Site of action of leptin (leptin increases satiety)
What is the function of the parvocellular region of the hypothalamus (lateral tuberal region)?
Receive inputs from ventral striatum (dopaminergic reward pathway)
“Feeding center”
Stimulation –> hyperphagia; lesion –> aphagia
Secretes orexin (only place in brain that makes orexin)
What are some functions of orexin and where is it synthesized
synthesized in the parvocellular region of the hypothalamus
Excitatory neurotransmitter
Increases body temp, locomotion, respiration
Promotes wakefulness, increases appetite
Manages the sleep/wake transition
What two areas of the brain balance each other to establish a set-point for body weight?
ventromedial nucleus and lateral hypothalamic area (VMN and LHA)
[both in the tuberal region of the hypothalamus]
What is the role of the mamillary bodies and what would a lesion here cause?
Part of the limbic system
Project to the hippocampus, important for consolidation of memory
Lesion: korsakoffs psychosis (temporal encoding deficits - sequence/timeline errors [confabulation])
What is the role of the posterior hypothalamus and what would a lesion here produce?
Responsible for controlling heat production
Lesion –> hypothermia
What is the function of the anterior hypothalamic area and what would a lesion here cause?
responsible for heat dissipation using descending autonomics
“thermostat of the body”
Lesion would cause hyperthermia and wild body temperature swings
What are the inputs and outputs of the Medial Geniculate Body of the thalamus and what would a lesion here cause?
Inputs: inferior colliculus (bilateral auditory information)
Outputs: Areas 41, 42, transverse gyri, amygdala
Lesion: subtle auditory deficits
What are the inputs and outputs of the Lateral Geniculate Body of the thalamus and what would a lesion here cause?
Inputs: retinal ganglion cells from contralateral visual hemifield
Outputs: Area 17, Amygdala
Lesion: contralateral homonymous hemianopsia
What are the inputs and outputs of the VPM nucleus of the thalamus and what would a lesion here cause?
Inputs: TTT carries pain/temp/touch from contra face, STT carries taste
Outputs: primary somatosensory cortex, insula
Lesion: at first, contra paresthesia followed by thalamic pain syndrome
Note: somatotopy present
What are the inputs and outputs of the VA/VL nuclei of the thalamus and what would a lesion here cause?
General somatomotor
Inputs: cerebellum (limb position), basal ganglia (movement sequence) both via the thalamic fasciculus
Outputs: motor-related cortical areas (primary motor, premotor, primary somsens)
Lesion: contra hemiataxia, choreiform movements
[in section, this is everything lateral to the anterior tubercle)
What are the inputs and outputs of the Mediodorsal nucleus of the thalamus?
Inputs: olfactory cortex, ALS (pain - emotional perception of pain), association cortices
Outputs: insula, PFC
What are the functions, inputs, and outputs of the Pulvinar/lateral posterior nucleus of the thalamus?
Functions: Visual responsiveness, attentiveness, orientation
Inputs: superior colliculus, pretectum, retina, somsens association cortex
Outputs: visual association cortex
Right pulvinar sees both visual fields, left sees only the right (can lead to spatial neglet with right side lesion)
