Limbic System Flashcards
where does limbic system mostly function
autocrine and endocrine function
–>mostly in response to emotional stimuli
subcortical parts of limbic system
olfactory bulb hypothalamus amygdala septal nuclei thalamic nuclei- anterior nucleus, dorsomedial nucleus
cerebral cortex aspects of limbic system
hippocampus
areas of neocortex- insular cortex, orbital frontal cortex, subcallosal gyrus, cingulate gyrus, parahippocampal gyrus, medial prefrontal gyrus
parahippocampal gyrus=
piriform cortex (primary olfactory cortex) entorhinal
most important parts of limbic system
insular cortex
orbital frontal cortex
cingulate gyrus
medial prefrontal gyrus
link between
THINKING part of brain in neocortex and EMOTIONAL RESPONSE in hypothalamus and septal nuclei
overall LS pathway
association neocortex–>limbic cortex–>limbic subcortical–>hypothalamus–>endocrine, autonomic, behavior
limbic cortex
subjective experience –what does stimuli mean to you?
what does it represent to you?
how should you react?
prefrontal cortex are areas
9,10,11,12
prefrontal cortex connects to hypothalamus via
medial forebrain bundle
prefronta cortex has reciprocal connections
- other areas limbic cortex (cingulate, medial temporal)
- amygdala
- septal nuclei
- dorsomedial nucleus of thalamus
lesion in dorsolateral pfc
executive fx difficulties..
- solving puzzles
- abstract reasoning and judgment
- dividing attention between tasks
lesion in orbital and medial PFC
emotional responses pfc
- moods (apathy in R, europhic in L)
- behavior (rude, tactless, inconsiderate)
orbital and medial PFC is effected strongly by
alcohol
what brain area has the greatest amount of growth in post natal development?
prefrontal coretx
depression
cingulate gyrus is overactive
posterior cingulate gyrus, dorsolateral pfc = underactive
depression is active in same areas as
chronic pain/suffering
fx of insular cortex
interoception
-visceral/autonomic responses (visceral pain)
==>assigns meaning to various signals and patterning some response through connections with amygdala and orbital frontal cortex
ADDICTION
connections of central olfactory pathways
anterior portion of temporal lobe and amygdala
pathway of olfactory
axons converge onglomeruli in olfactory bulb–>synapse with mitral dendrites
where do mitral cells project (3)
- olfactory tubercle in anterior perforated substance
- piriform cortex on rostral surface of uncus
- medial amygdala within uncus
after terminate in olfactory cortex, go to..
mediodorsal nucleus of thalamus
-(VP and ant perforated substance input)–>orbitofrontl cortex
ventromedial nucleus hypothalamus
- (input from medial amygdala via stria terminalis)
- emotional and endocrine rxns
septal region reciprocal connections
hippocampal formation - memory (cholinergic)
amygdala
hypothalamus (preoptic area)
additional efferents of septal region
mammillary body (hypothal) median eminence-->neuroendocrine regulation of reproductive behaviors (gnrh)
lesions in septal region
septal syndrome
–>behavioral overreaction–>”septal rage” with trivial stimulation
amygdala reciprocal affernts
solitary and parabrachail nucleus
limbic neocortex
thalamus (mediodorsal)
sensory and association areas of cortex
nonreciporcal afferent of amygdala
olfactory tract
efferents of amygdala
hypothalamus (stria terminalis & ventral amygdalofugal pathway)
limbiv neocortex
various central autonomic centters
fx amygdala
- relates environmental stimuli–>coordinated behavioral, autonomic, and endocrine responses
- feeding, drinking, fighting, mating, maternal care
- assigns emotional value to sensory cues in environ.
lesions in amygdala
reduce ANS and behavioral responses to stress
components of hippocampus
subiculum
CA1-CA4 pyramidal cell region
dentate gyrus that contains granule cells
curved part of hippocampus
cornu ammonis
cornu ammonis is divided
into 4 CA fields that contain prominent pyramidal cells
- blend into adjacent subiculum–> connected to entorhinal complex on parahippocampal gyrus of temporal lobe
perforant pathway
extends from entorhinal cortex–>dentate gyrus
hippocampus afferents
entorinal cortx (from neocortex) septum &hpothalamus (via fornix..from amy and association cortex)
hippocampus efferents
Ca fields and subiculum (reciporal to entorinal cortex)
fornix
postcommissural fornix
mamillary bodies, anterior nucleus of thalamus
precommissural fornix
septal nuclei, preoptic area, ventral striatum, orbital cortex, subcallosal cortex
hippocampus fx
glucocortiocoid hormone control movement mapping environment declarative memory (procedural, pattern, conditioned) place memory
damage to hippocampus leads to
only memory of recent events (more pronounced if entorhinal cortex involved)
Korsakoff’s psychosis
patient confabulate (pretend to know the answer but they get it wrong)
Mesolimbic Dopamine Reward System
VTA–>nucleus accumbens
Schizophrenia
decrease in DA through mesocortical systems–>PFC= negative symptoms (social withdrawal, decrease in outward emotional responsiveness)
increase in DA through mesolimbic system–>ventral striatal system (cortex, basal ganglia)
=positive symptoms- delusions, hallucinations
