lecture 15 Flashcards
(23 cards)
limbic loop
amygdala, hippocampus, orbitofrontal, anterior cingulate
–> ventral striatum –> ventral pallidum–> mediodorsal nucleus –> cortical targets (anterior cingulate, orbitofrontal cortex)
limbic system definition
higher order neural circuit that coordinates emotional responses
emotional “motor” system
characteristics of forebrain areas that process emotional signals
also mediate goal-driected behavior, interpretation and expression of social behavior, rational desicion making
subject to maladaptation in exposure to drugs
duchenne experiment
stimulate groups of muscles directly and activated different groups of muscles
discovered could make a fake smile but noticed missing eye muscles
2 pathways for activation of muscles in face
volititional movement - descending extra/pyrimidal projections from motor cortex and brainstem
(voluntary facial)
neural system for emotional expression - descending extrapyramidal projections from medial forebrain and hypothalamus
(emotional facial)
sham rage
if cut removes hypothalamus- have a very passive cat
if cut but leave in tact back of hypothalamus cat will look very angry “sham rage”
volitinional movements
lateral- fine control of distal extremeties
medial- proximal extremeties
emotional expression
medial- gain setting, rhythmical reflexes
lateral- specific emotional behaviors
brocas limbic lobe
originally thought to be olfactory function is processing emotion
modern limbic system
orbital/medial prefrontal cortex & cingulate gyrus amygdala mediodorsal nucleus of the thalamus ventral basal ganglia hypothalamus
components of limbic system no longer considered essential for processing
hippocampus- role in formation of memories but not expression
anteriro thalamus of the nucleus
parts of amygdala
medial- olfactory bulb
central- hypothalamus and brainstem
basal lateral- orbital and medial prefrontal cortex
associaiotional cortex of temporal lobe
ventral basal ganglia (not dorsal)
sends input to mediodorsal nucleus (thalamus)
sends input to orbital and medial prefrontal cortex
recieves input from amygdala
what information does basolateral amygdala recieve
highly processed sensory input
output from amygdala to hypothalamus allow it to influence activity in both somatic and visceral motor systems
prefrontal and temporal cortical connections
provide input from circuits that integrate emoitonal signifcance
what happens with removal of amydgala
removes aggressive and fearful behavior
- amygdala mediates neural processes that invest sensory experienece with emotional significance
pathway for conditioned fear
medial geniculate nucleus - amygdala - output to circuits that govern somatic and visceral motor activity
positive and negative reinforcers
positive- appetitive
negative - aversive
neitral
case study
- amydgala is needed for humans to experience fear
- amygdala is necessary for humans to recognize fear in others
affective disorders
clinical depression is associated with increased blood flow in limbic system structures
simplified limbic loop
cortical input–> striatum –x pallidum –x thalamus –> cortex
- disinhibitory circuit mediated through basal ganglia
- medium spiny type neurons
DAergic modulation of limbic system
projections from ventral tegmentum not SNPC
doesnt degenerate in parkinsons
drugs affect dopamine projection from VTA to NA
blocks serotonin and norepinepherine re uptake
leave more in the synapses but end up down regulating and can no longer operate at basal levels
dampens the natural response of emotion reinforcement circuitry
