What is the thalamic nuclei responsible for?
1. Relay general & special sensory information
2. Receive inputs from cerebellum & basal ganglia
3. Relay to associative & limbic cortical areas
Why is the thalamus important?
it consists of numerous nuclei, most with extensive reciprocal connections with the cerebral cortex
What is the direction of fibers that project from the functional thalamic nuclei?
Majority project to ipsilateral cerebral cortex
- precise, point-to-point projections between thalamic nuclei & defined cortical regions
What are the five (5) thalamic nuclei that make up the lateral nuclear group?
1. Ventral anterior
2. Ventral lateral
3. VPM/VPL [ventral posteromedial nucleus/v. posterolateral]
4. LGN [Lateral geniculate nucleus]
5. MGN [Medial geniculate nucleus]
What does the ventral anterior thalamic nuclei do?
basal ganglia & primary/supplementary motor areas
What does the ventral lateral thalamic nuclei do?
basal ganglia, cerebellum, & primary/supplementary motor areas
What does the VPM/VPL thalamic nuclei do?
spinothalamic tracts & medial lemniscus, trigeminothalamic tracts
What does the LGN thalamic nuclei do?
What does the MGN thalamic nuclei do?
The reticular nuclei (brainstem) of the reticular activating system are ______. They are located where?
diffuse and ill-defined, and have little apparent internal organization
- located at midbrain, pons, & medullary levels
What does the reticular activating system (RAS) control? It is interconnected with _____ & _____ in the brainstem.
Controls states of consciousness, sleep, REM, heart rate & respiration
1. basal nuclei
2. motor centers
Descending reticulospinal tracts originate _____ & _____ and influence _____ & ______.
Originate from the medullary and pontine RAS.
Influence muscle tone and posture
Raphe nuclei are a series of _____ nuclei that extend throughout the ________.
length of the brainstem
What neurotransmitter are Raphe nuclei responsive to?
Most are serotonergic
Where do the ascending projections of Raphe nuclei go to? (6)
6. widespread regions of cerebral cortex
What are Raphe nuclei believed to be involved in?
mood & cognitive function & in the neural mechanisms of sleep
What is the hypothalamus and what surrounds it?
small anatomical region of the diencephalon that is separated superiorly from the dorsal thalamus by the hypothalamic sulcus
Rostral = lamina terminalis
Lateral = substantia innominate (rostral) & medial edge of the posterior limb of the internal capsule (caudal)
Medial = inferior portion of 3rd ventricle
Caudal = merges into the midbrain tegmentum & PAG [periaqueductal gray]
[according to Dennis, location is pretty low-yield but still included]
What is the hypothalamus involved in?
control of visceral functions & emotional behavior
What is the preoptic area of the hypothalamus?
transition region that extends rostrally, forms a continuation with basal forebrain
What is the preoptic area of the hypothalamus composed of?
medial and lateral preoptic nuclei
Medial preoptic nucleus contains neurons that make GnRH
What is the periventricular zone of the hypothalamus adjacent to and what does it do?
adjacent to 3rd ventricle
- synthesizes releasing hormones
- projects via hypophyseal portal system to anterior pituitary
What is the medial zone of the hypothalamus and what "regions" does it contain?
cell-rich region composed of many nuclei
- Supraoptic (chiasmatic) region
- Tuberal region
- Mammillary region
What does the Lateral zone of the hypothalamus contain and what does it interconnect?
contains medial forebrain bundle
- interconnects lateral zone w/ the septal nuclei & the brainstem RF (reticular formation)
What else does the Lateral zone of the hypothalamus contain other than the medial forebrain bundle? And what does it do?
Lateral hypothalamic nucleus - which is a large cell group that constitutes the "feeding center"
What are the three (3) regions of the nuclei of the medial zone of the hypothalamus?
1. Supraoptic region
2. Tuberal region
3. Mammillary region
What three (3) nuclei does the supraoptic region of the medial zone of the hypothalamus?
1. Supraoptic/Paraventricular nucleus
2. Suprachiasmatic nucleus
3. Anterior nucleus
What is the supraoptic/paraventricular nucleus of the supraoptic region of the medial zone of the hypothalamus?
contains oxytocin (SO) & ADH (PVN), and transmit these substances to the posterior pituitary
Describe what the anterior & medial nuclear groups & intralaminar groups of the functional thalamic nuclei do and why are they different than the five (5) that make up the lateral nuclear group?
- 'non-specific' nuclei
- largely project to broad limbic & hypothalamic areas
- among these, the lateral dorsal nucleus is part of the limbic system
- instinctive drives, mood, emotional behavior
What is the anterior nucleus of the supraoptic region of the medial zone of the hypothalamus?
participates in a range of visceral/somatic functions, many neurons involved in temperature regulation
What are the three (3) nuclei that make up the tuberal region of the medial zone of the hypothalamus?
1. Ventromedial nucleus
2. Dorsomedial nucleus
3. Arcuate nucleus