DSA 3: Hypothalamus and Limbic System Flashcards
How does the hypothalamus specifically regulate homeostasis?
Water and electrolyte balance Food intake Blood pressure Circadian rhythm Stress response Body metabolism
What is the anterior (rostral) border of the hypothalamus?
Optic Chiasm
What is the posterior (caudal) border of the hypothalamus?
Midbrain (tegmentum/PAG)
What does the hypothalamus continue into?
Infundibular stalk and posterior pituitary
Are mammillary bodies found on the anterior or posterior part of the hypothalamus?
Posterior
What is the tuber cinereum?
Small swelling between optic chiasm and mammillary bodies - composes part of the floor
What is the median eminence?
Arises from tuber cinereum and eventually becomes infundibulum
What are three longitudinal divisions of the hypothalamus?
Anterior region
Tuberal region
Posterior region
What divides the medial and lateral zones of the hypothalamus?
Fornix
What happens if the lateral zone of the hypothalamus is damaged?
Decrease in feeding behavior that can lead to weight loss
What nuclei are found in the supraoptic region of the medial zone?
Supraoptic nucleus
Paraventricular nucleus
Suprachiasmatic nucleus
Anterior nucleus
What does the supraoptic nucleus do?
Contain ADH
What does the paraventricular nucleus do?
Contain oxytocin
What happens if there are lesions to the supraoptic and paraventricular nucleus?
Diabetes Insipidus
Increase water intake
Increase urination
What does the suprachiasmatic nucleus do?
Receives retinal input and involved in circadian rhythms
Indirectly controls melatonin secretion in pineal gland
What does the anterior nucleus do?
Range of visceral/somatic functions including temperature regulation
What does the medial mammillary nucleus do?
Receive afferents from hippocampus via fornix
Efferents to thalamus and brainstem
What happens if there is a lesion to the medial mammillary nucleus?
Inability to process short-term events into long term memory
What does the ventromedial nucleus do?
Satiety center (tells that body is full)
What happens if there is a lesion to the ventromedial nucleus?
Excessive eating leading to abnormal weight gain
What does the dorsomedial nucleus do?
Subserves functions of emotional behavior and can cause sham rage
What happens if there is a lesion to the dorsomedial nucleus?
Decrease in aggression and feeding
What does the anteromedial group of the Circle of Willis supply?
Pre-optic and supraoptic region
Septal nuclei
Rostral portions of lateral hypothalamic area
What does the posteromedial group of the Circle of Willis supply?
Tuberal and mammillary region
What is the role of the fornix?
Transmits information from hippocampus to hypothalamus
What is the role of the medial forebrain bundle (MFB)?
Transmits information from septal nuclei, midbrain tegmentum, and hypothalamus itself to hypothalamus through lateral hypothalamic zone
What is the role of the amygdalohypothalamic fibers?
Transmits information from septal nuclei, pre-optic area, and medial hypothalamic zone to hypothalamus
What is the role of the mammillary fasciculus?
Transmits information from medial mammillary nucleus to anterior nucleus, playing a role in circuit of Papez
What is the role of the hypothalamic fibers?
Transmits information from lateral pre-optic area to dorsomedial nucleus of the thalamus and amygdaloid nucleus
What is the supraoptichypophyseal tract?
Composed of axons from supraoptic and paraventricular nucleus to the posterior pituitary to release oxytocin and
What is the tuberoinfundibular tract?
Inputs from hypothalamic neurons to anterior pituitary
What is the role of the limbic system?
Influence behavior, memory, and pain perception
What structures compose the hippocampus?
Subiculum
Entorhinal cortex
Dentate Gyrus
CA1, CA2, CA3, CA4
What is the afferent pathway of the hippocampus?
Dentate gyrus –> CA3 –> CA1 –> subiculum
What is the efferent pathway of the hippocampus?
Subiculum –> fornix
What are the afferents of the cingulate gyrus?
From the thalamus and cortex
What are the efferents of the cingulate gyrus?
To the entorhinal cortex of hippocampus
What is the stria terminalis?
Outputs to hypothalamus and basal ganglia to permit motor behavioral responses from amygdala
What is the ventral amygdalofugal pathway?
Efferent pathway: amygdala to various parts of the brain
What is the Papez circuit?
Neural circuit for the control of emotional expression
What is the function of the septal region?
Control rage of behavior
What is the function of the ventral tegmental area?
Reward
Motivation
Role in addiction
What happens if there is a bilateral lesion of the hippocampus?
Anterograde episodic memory (cannot learn new memory)
What structures are damaged in Korsakoff’s Syndrome?
Mammillary bodies
Hippocampal complex
Dorsomedial thalamic nucleus
What happens with patients who have Korsakoff’s Syndrome?
Impedes retention of newly acquired memory
Short term memory doesn’t become long term memory
Will be confabulate (fragmented memories)
What is phantosmia?
Distortion in a smell experience or the perception of a smell when no odor is present
What is Kluver Bucy syndrome?
Bilateral temporal lobe lesions that abolish amygdaloid complex leading to: Visual agnosia Hyperorality Hypermetamorphosis Placidity Hyperphagia Hypersexuality
