DSA-Hypothalamic And Limbic Systems Flashcards
Hypothalamus Function
Maintenance of homeostasis
Hypothalamus Location
Just posterior to optic chiasm, posterior merges into tegmentum and PAG, forms floor and ventral walls of 3rd ventricle
Mammillary Bodies
Posterior part of hypothalamus
Tuber Cinereum
Small swellings b/t mammillary bodies and optic tracts
Median eminence
Arises from tuber cinereum and narrows into infundibulum
Nuclei of Medial Zone of HT: Supraoptic Region
Supraoptic/paraventricular nucleus:
-contain oxytocin and ADH
—lesion results in diabetes insipidus (=increase H20 and urination)
Suprachiasmatic Nucelus
-retinal input; involved in circadian rhythms
Anterior Nucelus
-range of visceral/somatic fxns
Nuclei of Medial HT: mammillary region
Medial mammillary nucleus
-afferents from hippocampus via fornix
-efferent to thalamus and Brainstem
—lesions=inability to turn short term memory into long term
Tuberal Region of Hypothalamus
Ventromedial nucleus
-satiety venter
—lesions result in excessive eating
Dorsomedial Nucelus
-emotional behavior; stimulation causes sham rage
—destruction results in decreased aggression
Blood Supply to HT
Anteromedial group
-anterior comm and ACA
Posteromedial Group
-Posterior comm and PCA
—rostral part of PComm=tuberal, caudal part of PComm=mammillary
Afferents to HT
Fornix
-from subiculum and hippocampus
—largest single input to HT
Medial Forbrain bundle
-interconnects septal nuclei, HT and Midbrain
Amygalohypothalamic Fibers
-stria terminalis and Ventral amygdala fugal pathways
Efferent from HT
Mammillary Fasciculus
-originates from medial mammillary nucleus
—splits into mammillothalamic and mammilotegmental tracts
—important part of circuit of Papez
Hypothalamothalamic Fibers
-from lateral prep-tic area to dorsomedial thalamus and amygdala
HT Direct link to ANS
Hypothalamomedullary Fibers
-to solitary nuc, dorsal Vargas motor nuc and nucleus Ambiguus
Hypothalamospinal fibers
-intermediolateral cell column
—lesions to anterolateral medulla disrupts (Horners)
Indirect Link of HT to ANS
Posterior Longitudinal Fasciculus and Mammillotegmental Tract
-target PAG, which will then go to other areas of Brainstem
Supraopticohypophysial Tract
Made of axons of neurons in SON and PVN
-produce Oxytocin and ADH, which is stored in Herring bodies
Tuberoinfundibular Tract of HT
Input from neurons in Periventricular zone, convey releasing hormones to median eminence and infundibulum
Hippocampal Formation Afferent Pathway
Dentate Nucleus to CA3–>CA1–>subiculum
Hippocampal Formation Efferent Pathway
Subiculus—>fornix
-projects to medial mammillary nuc, ventromedial nuc and anterior nucleus
Amygdala afferent pathway
From Interior temporal association cortex, thalamus, and brainstem
Amygdala Efferent pathways
Stria Terminalis
-output to hypothalamus and basal ganglia for motor responses
Ventral Amygdalofugal Pathway
-many areas of the brain
Papez Circyuit
Cingulate Gyrus—>hippocampus
Hippocampus—> Fornix—>medial mammillary Nuclei
Medial Mammillary Nucleus—>anterior nucleus
Anterior Nucelus—>cingulate gyrus
Septal Region of Limbic Structures
Rostral to anterior commissure and control of rage behavior
Nucleus Accumbens of Limbic Structures
Plays important role in addiction and chronic pain
Efferents to HT, brainstem, and globus pallidus
VTA of Limbic System
Medial to substantia nigra
-connections w ventral striatum
Efferents to Nucleus Accumbens and plays role in reward and motivation
Hippocampal Amnesia
Bilateral lesion of hippocampi
-cannot learn new material (anterograde episodic memory) and spared procedural and working memory
Korsakoff’s Syndrome
Thiamine Def; associated with chronic alcohol use
-impedes retention of newly acquired memory through degradation of mammillary bodies, hippocampus and dorsomedial nucleus
Difficulty understanding written material and meaningful convos
Anosmia
Loss of smell through viral infection, obstruction, or congenital defect
Phantosmia
Distortion in a smell experience or perception of smell when not present
-lesion of anterior/medial temporal lobe
Kluver-Bucy Syndrome
Bilateral temporal lobe lesions that abolish amygdala
- Visual agnosia
- hyperorality (examine objects by mouth)
- hypermetamorphosis (overreact to visual stim)
- placidity (may not show fear when they should)
- Hyperphagia
- hypersexuality
Uncal herniation
Uncut and parahippocampal gyrus over edge of tentorium cerebelli
-CN III, CST, and CBT all affected
