Limbic system Flashcards
What structures does the hippocampus receive inputs from?
Parahippocampal gyrus sends inputs to hippocampus from:
Olfactory
Amygdala
Cingulate gyrus
Contralateral info from hippocampus
Directly from amygdala
What structures does the hippocampus send outputs to?
Parahippocampal gyrus
Contralateral hippocampus
Mamillary bodies (via the fornix)
What structures are involved in intermediate-term declarative memories?
Hippocampus and associated cortical areas
What structures are involved in intermediate-term implicit memories?
Cerebellum, basal ganglia, amygdala and associated areas
What types of memories is the Papez circuit involved in forming?
Intermediate term memories
What happens to long-term memories with hippocampal damage?
Nothing - they are stored more diffusely
What leads to anterograde amnesia?
Bilateral destruction of the hippocampus (causes inability to form new memories)
Korsakoff syndrome is caused by what?
What are the symptoms?
Damage to the mamillary bodies and MD of the Thalamus - caused by B1 deficiency (often associated with chronic alcoholism, but ultimately is due to malnutrition)
Anterograde amnesia and confabulation are the symptoms
What causes Alzheimer’s Disease?
What are the symptoms?
Amyloid plaques and tangles build up and lead to neuronal death - first in the hippocampus, the cortex also degenerates relatively early on
Symptoms are anterograde amnesia with hippocampal damage, retrograde amnesia with cortical damage - leads to dementia
Where is the amygdala located?
Beneath the uncus of the temporal lobe, at the anterior end of the hippocampus and the lateral ventricle, CLOSE to tail of caudate (not at end of tail of caudate)
What structures does the amygdala receive inputs from?
Pre-frontal cortex, temporal cortex, Cingulate gyrus (processed sensory info)
Olfactory bulb (direct)
Visceral sensory information from brainstem
Hypothalamus and septal nuclei
What structures does the amygdala send outputs to?
Hippocampus and parahippocampal gyrus for formation of memories
Hypothalamus for autonomic responses to emotions
Nucleus accumbens for motivation and reward
MD nucleus of thalamus, which leads to prefrontal cortex for conscious perception of emotions
What are some functions of the amygdala?
Conscious perception of emotions
Visceral response to emotions
Role in formation of memories
Motivation and reward (influences drive related behaviour)
What syndrome can lesions to both amygdala cause?
What are the symptoms?
Kluver-Bucy Syndrome
Symptoms: decreased fear response, decreased aggression, increased sexual drive, increased eating
What is the mechanism behind anxiety?
Prefrontal cortex has reduced control over the amygdala, amygdala becomes over-active
