Hypothalamus & Limbic Flashcards
What is the main function of the hypothalamus?
Maintains homeostasis (feeding, thirst, salt, thermoregulation, sleep, sickness) and special survival drives (sexual behavior, parenting, social, curiosity, aggression)
What is the function of the arcuate nucleus of the hypothalamus?
Release hormones for anterior pituitary. Affected by stress.
What is the function of the suprachiasmatic nucleus?
Biological clocks: circadian and circannual
What is the function of the paraventricular nucleus?
Anterior & posterior pituitary hormones
Autonomics
What is the function of the mammillary nucleus?
Memory (from hippocampus via fornix)
Spatial memory/position of head in space
To brainstem reticular formation and anterior thalamic nuclei
What is the Papez circuit?
The limbic circuit between the hypothalamus, cortex, hippocampus and amygdala
Is the pathway of the Papez circuit?
Hippocampus through fornix to mamillary body, through mammilothalamic tract to anterior nucleus of thalamus, to cingulate gyrus, back to hippocampus.
There are also hippocampal projections to the amygdala, which go the the hypothalamus and then to the association cortex before returning to the hippocampus.
Which part of the pituitary is involved with direct activation and which is involved with indirect activation?
Direct: posterior pituitary = neurohypophysis
Indirect: anterior pituitary = adenohypophysis
List the nuclei of the amygdala and their primary function
Medial: olfactory system
Central: emotional responses
Basolateral: Link experience of emotions and their expression
What are the major inputs to the amygdala?
Sensory input: sights, sounds, touches, smells, tastes
Olfaction to the medial, the rest to the basolateral
Visceral sensory inputs reach the central nuclei
What are the fiber tracts leaving the amygdala?
Stria terminalis and ventral amygdalofugal pathway
What is the overall function of the amygdala?
Important role in analyzing whether a remembered event is good or bad, and triggering the appropriate response
Crucial for conditioned responses, fear response
What is Kluver-Bucy syndrome?
Bilateral lesions to the tips of the temporal lobes causes Docility, Hyperphagia, Hyperorality, Hypersexuality and visual agnosia
How many layers make up the hippocampus?
3 layers: CA1, 2 and 3
Where do inputs to the hippocampus originate?
Cortex via the entorhinal cortex
Septal nuclei via the fornix
Amygdala
Where do the outputs from the hippocampus go to?
Cortex via the entorhinal cortex
Mamillary bodies via the fornix (to limbic cortex)
What form of memory is lost in Alzheimer’s disease?
Declarative memories. Patients cannot form new memories (anterograde amnesia). Nondeclarative memories (skills/procedures) are unaffected.
What is Wernicke-Korsakoff syndrome?
Thiamine deficiency often associated with alcoholism
Wernicke’s encephalopathy (acute phase) and Korsakoff’s amnesic syndrome (chronic phase)
What is hippocampal sclerosis?
Severe neuronal cell loss and gliosis of the CA1 region and subiculum of the hippocampus. Similar presentation to Alzheimer’s.
What are the functions of the septal nuclei?
Regulates gonadal hormone secretion, reproductive and sexual behaviors
Facilitates memory formation
Lesions of the septal nuclei cause what?
Septal rage: behavioral overreaction
What is Pick’s disease?
Frontotemporal dementia causing progressive destruction of neurons
Buildup of tau proteins in neurons (Pick bodies)
