Hypothalamus Flashcards
The hypothalamus is critically involved in coordination and integration of _____, _____, and _____ responses necessary for the maintenance of ____ and ____ rhythms, _____ cycles, _____regulation, the balance of ____, and name three other
autonomic, endocrine and behavioral circadian and circannual sleep/wake thermo fluid electrolytes energy reproduction food ingestion agnostic behavior
Describe the location of the hypothalamus
Ventral diencephalon
Continuous across the midline, extends from the floor to wall of third ventricle
Continues posteriorly with brainstem (ventral tegmentum, which is part of the midbrain)
Rostral boundary: plane formed between Foramen of Monro and center of optic chiasm; diagonal band of Broca
Dorsal boundary: caudal septum, anterior commissure
How can you divide the hypothalamus and what provides the boundary line
Fornix divides hypothalamus into lateral and medial parts. The medial parts control pituitary, the lateral part is comprised of the medial forebrain bundle. Medial has dorsal part. Rest of the medial hypothalamus can be divided into preoptic (anterior), tuberal, and mammillary bodies (posterior).
Others have divided the hypothalamus across sections parallel to the midline -> Periventricular (region surrounding the third ventricle and closest to midline), medial & lateral
Differences between preoptic and mammillary bodies
Preoptic is technically part of the telencephalon but functions like the diencephalon in that there are clusters of nuclei modulating behavior. The mammillary bodies receives input from the fornix and acts different from the rest of the hypothalamus and is not involved in pituitary related processes.
List the nuclei and areas of the hypothalamus
Preoptic: periventricular preoptic n (PePn), medial preoptic n (MPN). lateral preoptic area (LPA); Anterior: suprachiasmic n. (SCH), paraventricular n (PVH), anterior hypothalamic n. (AHN) lateral hypothalamic a (LHA), supraoptic n. (SO); Tuberal: infundibular n (INF), ventromedial n. (VMH), dosomedial n. (DMH), tuberomamilary n. (TM), lateral hypothalamic a. (LHA); Mamillary: Posterior hypothalamic a. (PHA), dorsal premamillary area (PMD), ventral premamillary area (PMV), medial mamilary n. (MM), lateral mamillary n. (LM), tuberomamilary n. (TM), lateral hypothalamic area (LHA)
Specialized kind of glia cells along the third ventricle. What do they do?
tanycyte
They extend into the hypothalamus, transmits signals from CSF to nervous system
Describe the divisions of the pituitary gland
Anterior (adenhypohysis) and posterior (neurohypophysis).
Note: hypophysis is another name for pituitary and it’s greek for ‘lying under’
Transition zone divisions and their functions
Mesocortical zones:
periarchicortex: limbic zone with 5 layers, interconnected areas between ACC, entorhinal cortex, retrosplinal cortex, infralimbic cortex, parasubiculum, presubiculum
proneocortex: paralimbic zone like regular neocortex, interface between neocortex and periarchicortex; posterior cingulate, perirhinal areas (area around the rihnal fissure), prelimbic cortex
Afferents to the hippocampal formation
1) Corticohippocampal (lots of pitstops)
2) Entorhinal cortex (entorhinal-hippocampal projection) -> topographically organized
3) Amygdala
4) Medial septal nucleus and nucleus of the diagonal band (part of theta rhythm) -> fornix, cingulum, MFB & amygdala
5) Mam Bodies
6) brainstem monoamine system
7) Thalamus
Efferents to the hippocampal formation
Efferents via fornix: from Ammon’s horn (hippocampus proper itself) to lateral septal nucleus; from subiculum to precommissural fornix (front of the anterior commisure) and to postcommissural fornix (mam.body…)
non-fornical efferents: neocortex, amygdala
The different afferents of the entorhinal cortex
dorsal/splenial part temporal part
lateromedial axis of entorhinal cortex -> spleniotemporal (or top to bottom) axis of hippocampus)
lateral (that goes to top) - sensory
medial (that goes to bottom) - other stuff on what’s going on in body, from subcortical centers
Dentate gyrus layers
cell body: granular layer
apical dendrities: molecular layer
axons: polymorphic layer/hilus
these layers are important because they all get diff inputs
Pathway from afferent to proper via dendrate gyrus
entorhinal afferents -> dendrites of granule cell in molecular layer -> somata in granular layer -> axons of granule cell in polymorphic layer (glutamate;excitatory) -> enter the hippocampus proper as mossy fibers and synapse with thorny excretenances of the pyramidal cells in the hippocampus proper (CA3) that are in the stratum radiatum -> CA1 (apical or basal dendrites) which is main output of hippocampal horn -> subiculum (main) and entorhinal -> presubiculum -> parasubiculum -> entorhinal
Characteristics regarding the dg interneurons
intrinsic interneurons in dg are aspiny and GABAergic (although polymophic layer has some excitatory interneurons, i.e. mossy cells that exist in polymorphic layer and also synapse with granule cells )
hippocampal proper
dendrites in stratumum radiatum
terminals in stratum lacunosum moleculare
axones enter alveus and remain in proper or go to entorhinal or lateral setpum via fornix
