Limbic System Flashcards
Limbic system input and output
input from sensation/cortex/ANS
output to cortex/ANS/motor
4 F’s of ANS and what control
Fighting, fleeing, feeding, fornicating
controls viscera
2 divisions of ANS and where located
Parasympathetic - preserve energy, rest/digest, craniosacral
Sympathetic - expend energy, fight/flight, thoracolumbar
Complementary roles of ANS systems
Para - contract pupil, inhibit tear, inc saliva, slow heart, constrict bronchi, inc digest, constrict bladder, stimulate blood in genitals
Sympa - dilate pupil, stim tears, inhib saliva, accelerate heart, dec digestion, adrenaline, inhibit bladder constriction, inhibit genital blood
5 parts of limbic system
Hypothalamus, mammillary bodies, hippocampus, amygdala, limbic cortex
Hypothalamus
underneath ventral brain stem between optic chiasm and mamm bodies
collection of opposing nuclei for ANS and hormones
Hippocampus function and connections
consolidate memory/spatial memory
input from entorhinal cortex, output through fimbria and fornix to mamm bodies and hypothal
share connections with amygdala and sensory systems (intertwine sensation/memory)
Hippo circuitry
Entorhinal cortex -> Dentate gyrus -> CA3 (cornis ammonis) -> CA1 -> output through fimbria & fornix
neurogenesis
new cells born in dentate gyrus of hippo throughout life
new cells also born in olfactory bulb (only places this happens, olf. bc air toxins kill)
Amygdala functions and location relation to hippo
almond shaped anterior to hippo
fear/rage/aggression/sexual (high valence behaviors)
Low Road of amygdala
Central nuclei, fast automatic
input: low level sensory
output: ANS and modulatory (norepinepherine)
Controlled by medial prefrontal cortex
High Road of amygdala
Basolateral nuclei, slow cognitive
Input: hippo, association cortex, sensory cortex/thal (processed filtered info)
Output: medial prefrontal cortex, assoc. cortex, ventral striatum and nucleus accumbens (override fear with reward)
Controlled by medial prefrontal cortex
Korsakoff Syndrome
cause by thiamine deficiency (alcoholism = no food)
damage to mammilary bodies and limbic thalamus (mamm connected to hippo)
Symptoms of amnesia and confabulation
Toxoplasmosis
Parasite in cat guts
Infects amygdala of rats = no fear response to cats, get eaten by cats
dangerous to human fetus
Kluver-Bucy Syndrome
bilateral lesion of medial temporal lobe
Symptoms: hyperphagia (eat too much), hypersexuality (indiscriminate mating), docility, amnesia
