Hypothalamic and Limbic Systems Flashcards
what is the main role of the hypothalamus?
it is a regulator of homeostasis, ANS, and endocrine function
what forms the posterior part of the hypothalamus?
the mammillary bodies
How is the hypothalamus divided up?
Into a medial and lateral zone and then the medial zone has an anterior, middle, and posterior area
what nuclei make up the anterior area?
paraventricular nucleus, preoptic nucleus, anterior nucleus, supraoptic nucleus, and suprachiasmatic nucleus
what nuclei make up the middle area?
the arcuate nucleus, the ventromedial nucleus, and the dorsomedial nucleus
what makes up the posterior area?
the posterior nucleus and the mammillary body
what would damage to the lateral zone result in?
decrease in feeding (weight loss)
what is significant about the supraoptic/paraventricular nuclei located in the anterior area?
they contain oxytocin (PVN) and ADH (SON)
what would a lesion of the supraoptic/paraventricular nucleus result in?
diabetes insipidus, increase H20 intake, and increase urination
what is significant about the suprachiasmatic nucleus?
it receives retinal input and is involved in circadian rhythms
what is significant about the ventromedial nucleus in the middle area?
it is the satiety center
what would a lesion of the ventromedial nucleus result in?
excessive eating and abnormal weight gain
what is significant about the dorsomedial nucleus in the middle area?
emotional behavior- stimulation causes sham rage
what would destruction of the dorsomedial nucleus result in?
decreased aggression and feeding
what is significant about the arcuate nucleus?
it secretes releasing/ inhibiting hormones
what afferents does the medial mammillary nucleus in the posterior area receive?
afferents from the hippocampus via the fornix
what would a lesion of the mammillary bodies result in?
an inability to process short-term events into long-term memory
What is the blood supply for the anteromedial group of the hypothalamus?
branches from the anterior communicating and anterior cerebral arteries
what is the blood supply of the posteromedial group of the hypothalamus?
perforating arteries from the posterior communicating artery and posterior cerebral artery
what is the stria terminalis and ventral amygdalofugal fibers?
afferent fibers from the amygdala to the hypothalamus
what is the corticohypothalamic input?
afferent input from the orbitofrontal and cingulate area; multiple association areas; frontal lobe to the lateral zone
what do the retinohypothalamic fibers target?
the suprachiasmatic nucleus in the hypothalamus
efferents from the medial zone and mammillary bodies enables what?
the hypothalamus to influence emotional aspects of behavior
where do efferents from the medial zone and mammillary bodies target?
the PAG and the RF
where do efferents from the mammillothalamic tract project to?
to the anterior nucleus of the thalamus which then sends projections to the frontal lobe
where do efferents from the lateral zone of the hypothalamus project to?
the DM nucleus of the thalamus, which then sends projections to the frontal lobe
what is the supraopticohypophysial tract made up of?
axons of neurons in the SON and PVN
where is oxytocin and ADH stored before being released into the capillary plexus of the posterior pituitary?
herring bodies
what is significant about the tuberoinfundibular tract?
it conveys releasing hormones to median eminence and infundibulum
the anterior area of the hypothalamus activates what in relation to the ANS?
the parasympathetic activity
the posterior area of the hypothalamus activates what in relation to the ANS?
the sympathetic activity
what would a lesion of the anterolateral medulla disrupt and result in?
disrupts the hypothalamomedullary fibers–> sympathetic outflow to face and head (Horner’s syndrome)
what makes up the limbic system?
subcallosal area, cingulate gyrus, parahippocampal gyrus, uncus, hippocampal formation, amygdala, and septal nuclei
connections to and from the limbic system influence what?
behavior, memory, and pain perception
the limbic system is interposed between what two structures?
the hypothalamus and the neocortex
what is the hippocampal formation important for?
learning and memory
what makes up the hippocampal formation?
the subiculum, the hippocampus proper (ammon horn) the dentate gyrus and the parahippocampal gyrus
what is the anterior part of the parahippocampal gyrus knwon as?
the entorhinal cortex
how does afferent information enter the hippocampus?
dentate gyrus–> CA3–> CA1–> subiculum
where do efferent fibers from the hippocampus terminate?
in the medial mammillary nucleus, ventromedial nucleus, and the anterior nucleus
what is an uncal herniation?
movement of the uncus and possibly the parahippocampal gyrus downward over the edge of the tentorium cerebelli
what could cause a uncal herniation?
hemorrhagic lesion or tumor in the hemisphere
what are some signs of a uncal herniation?
dilated pupil and abnormal eye movement, double vision, weakness of extremities, later on respiration is affected and abnormal reflexes
what is korsakoff’s syndrome?
progressive degeneration of the mammillary bodies, hippocampal complex, and dorsomedial thalamic nucleus
what results from korsakoff’s syndrome?
it impedes the retention of newly acquired memory; short-term memory cannot become long term memory
what is korsakoff’s syndrome caused by?
thiamine deficiency, typically associated with chronic alcoholism
what is hippocampal amnesia?
bilateral lesions of the hippocampi
what results from hippocampal amnesia?
profound deficit in learning new material with spared procedural and working memory
what is the role of the amygdala?
it attaches emotional significance to a stimulus- emotional responses to food- visceral responses to emotional stimuli including pain
what would a lesion of the amygdala result in?
impaired recognition of fear, anger, and disgust in facial expression as well as vocal affect (fear and anger)
what is Kluver-Bucy Syndrome?
bilateral temporal lobe lesion that abolish the amygdaloid complex
What does kluver-bucy syndrome result in?
behavioral changes- hypersexuality, hyperphagia
