Limbic System Flashcards
what is the main function of the limbic system?
the assignment of value
**pretty much connected to everything
motivation, fear, anger, emotions, learning, memory,
what structures are associated with the limbic system?
amygdala
hippocampus
septal region
what are the 3 things that form the hippocampus?
what is the papez circuit?
1-dentate gyrus
2-hippocampus proper (archicortex)
3-subiculum
papez circuit -limbic system
(cingulate gyrus- hippocampus- fornix- hypothalamus (mammillary bodies)- thalamus- cortex
what is the function of the hippocampus?
formation of new memories and learning
-important in converting short term memories to long term
what would be the result of damage to the hippocampus? what is the specific name for this?
profound loss of recent or short-term memory and the ability to learn= anterograde amnesia
older memories from before injury are unharmed
intact hippocampus allows the animal to compare the conditions of a present threat with similar part experiences- thus enabling it to choose the best option, in order to guarantee its own survival
what is the location of the amygdaloid nucleus?
deep to the uncus
what is the function of the amygdaloid? what is its major afferent?
major afferent= smell
functions:
- important in behavior and emotions
- programs appropriate behavioral responses (anger, fear, sexual responses)
what are the results of a lesion to the amygdaloid?
bilateral lesion results in profound behavioral alterations
loose affective meaning of the perception of outside info, like the sight of a well known person. the subject knows exactly who the person is, but it not capable to decide whether he likes or dislikes them
what are the 3 nuclear divisions of the amygdala?
1- central nuclei
2-cortical nuclei
3- basolateral nuclei
describe the basolateral nuclei:
what does it do?
where does it project?
thalamus, sensory cortex–> basolateral nucleus
projects to:
- frontal lobe
- thalamus
- temporal lobe
functions:
- though to attach emotional significance to a stimulus
- links stimuli with particular emotions (hearing a sound)
what do central nuclei do?
mediates emotional response
regulates autonomic NS
helps shape responses to emotional stimuli
what do the cortical nuclei do?
olfactory perception
role in behaviors triggered by smell
where does the septal region send fibers to?
what is its function?
sends fibers to BS RF
- when the septal region is stimulated in conscious patients there are feelings of pleasure, optimism, euphoria, happiness
- involved with reward or pleasure (connection with hypothalamus)
- centers of orgasm
area of pleasure- dopamine goes here
nucleus accumbens of BG goes here
what is the cingulate gyrus? what does it do?
part of the cerebrum that lies closest to the limbic system, just above the corpus collosum
provides a pathway from the thalamus to the hippocampus
seems to be responsible for focusing attention on emotionally significant events and for associating memories to smells and to pain
what is the anterior cingulate cortex? how is it divided? what does it do?
can be divided anatomically- attributed to functions into:
- executive (anterior)
- evaluative (posterior)
- cognitive (dorsal)
- emotional (ventral)
ACC seems to be especially involve when effort is needed to carry out a task such as in early learning and problem solving
many studies attribute functions such as:
- error detection
- anticipation of tasks
- motivation
- modulation of emotional responses to the ACC
what is the ventral tegmental area?
people with damage here tend to??
area of the BS (just below the thalamus)
consists of dopamine pathways that seem to be responsible for pleasure
people with damage here tend to have difficulty getting pleasure in life– often turn to alcohol, drugs, sweets and gambling
what is the basal ganglia?
responsible for repetitive behaviors, reward experiences, focusing attention
what is the prefrontal cortex?
part of the frontal lobe which lies in front of the motor area
closely linked to the limbic system
besides apparently being involved in thinking about the future, making plans, and taking action, it also appears to be involved in the same dopamine pathways at the ventral tegmental area and plays a part in pleasure and addiction
what is Kluver-Bucy syndrome?
=bilateral removal of the temporal lobes
absence of emotional response so that fear, rage and aggression cease to exist (amygdaloid)
a compulsion to be overly attentive to all sensory stim (exam on object with all sensory modalities)
hypersexual
psychic blindness or visual agnosia (neocortical pathway to temporal lobe)= inability to recognize the meotional importance of events
what are Korsakoff Syndromes?
=loss of recent memory and a tendency to fabricate false accounts of recent events
hippocampus, maxillary bodies and esp medial dorsal thalamic nucleus
Alzeimer’s disease
what is alzeimer’s disease?
progressive dementia in patients under 65
associated with a loss of neurons in the hippocampal formation
