Limbic System Flashcards
this structure involved in earliest loss of alzheimer’s disease…memory loss
entorhinal cortex
blood supply to hypothalamus and anterior thalamus
circle of willis
efferent pathway of HF
CA1 - subiculum - alveus/fimbria/fornix - precommissural (to septal nuclei, frontal cortex, hypothalamus, nucleus accumbens) or postcommisural (to medial mammillary nucleus of hypothalamus)
cortical structures that form the limbic lobe (grand lobe limbique)
subcallosal area, cingulate gyrus and isthmus of cingulate, parahippocampal gyrus (and hippocampal formation),uncus
visceral and motor responses of limbic system
homeostatic functions, olfaction, memory, emotion and drives (also reproduction, defense)
input to the septal area
hippocampus and amygdala
output of septal nuclei to the habenular nuclei via this
medullary stria thalamus
this output of septal area enables limbic system to influence visceral responses to emotion events
medullary stria
blood supply to hippocampal formation, amygdala, stria terminalis
anterior choroidal
3 primary regions of hippocampal formation
dentate gyrus, hippocampus proper, subiculum
plays key role in temporal lobe memory system, declarative memory
hippocampus
where are neurofibrillary tangles found in Alzhemier disease?
subiculum and entorhinal cortex
major efferent connections from hippocampus travel via this
subiculum
refers to major structures of limbic system
medial temporal lobe
CA3 projects to CA1 pyramidal cells via these (connect CA3 to CA1); what does this allow?
Schaffer collaterals; long-term potentiation
these help hippocampus ‘map’ the environment…take visual/olfactory/motor sensations to build memory (creates context)
place cells
afferent hippocampal circuitry (*perforant pathway*)
entorhinal - granule of Dentate gyrus - dendrites pyramidal CA3 - fornix or CA1 pyramidal cells - fornix
where is working memory located?
dorsolateral prefrontal cortex
synaptic layer of hippocampal formation
molecular
primary neuron in dentate gyrus
granule cell
CA1 pyramidal cells leave hippocampus via this
fornix
majority of symptoms seen in Kluver Bucy syndrome are due to damage/removal of this
amygdala
subcortical nuclei included in limbic system
septal, nucleus accumbens, hypothalamic, thalamic, habenular
NT for projections from septal nuclei/nucleus accumbens to HF
Ach
how many layers does paleocortex have? where is this found?
3-5; entorhinal and piriform
where is hippocamapal formation found?
medial wall inferior horn LV
afferent connections with entorhinal cortex via this (across hippocampal sulcus)
perforant pathway
this generates freezing/avoidance behavior in stress response
PAG
outputs of septal region
habenular nuclei, midbrain tegmentum, hippocampus
septal region projects to the midbrain tegmentum via this
MFB
where does subiculum project (after innervation by CA 1-3, from dentate fibers)?
entorhinal cortex and alveus/fimbira/fornix
blood supply to subcallosal area, cingulate gyrus and isthmus
ACA (cingulate/isthmus from pericallosal br.)
efferent fibers of granule cell layer in dentate gyrus; where do these project?
mossy fibers; CA 1-3 (which projects to subiculum)
broadmann’s area for entorhinal cortex
28 (5 layer cortex)
what NT is found in ventral tegmental area? where is this VTA found?
dopamine; interpeduncular fossa
amygdala projects to septal area via these pathways
stria terminalis and VAFP
subcortical tracts that are part of the limbic system
amygdaloid complex, substantia innominata, ventral tegmental area, PAG, prefrontal cortex, afferent fiber bundles
no longer show fear or anger (sign of Kluver Bucy syndrome)
placidity
symptom of Kluver Bucy syndrome…compulsion to explore immediate environment
hypermetamorphosis
where do CA3 pyramidal cells project?
leave via fornix or CA! pyramidal cells (via Shaffer collaterals)
bilateral destruction of temporal lobes (amygdala) leads to this
Kluver Bucy syndrome
output of accumbens nucleus
ventral pallidum and MD thalamus
this output of septal area associated with experiencing pleasure or reward
MFB
where does ventral amygdalofugal pathway project from?
basolateral group and central nucleus of corticomedial group
what layer of neocortex is pyramidal layer of hippocampal cortex continuous with?
layer 5
Papez circuit
HF - fornix - MB - MTT - anterior nuc. thalamus - thalamocingulate radiation - cingulum - association cortex - entorhinal cortex
afferent fiber bundles that are part of limbic system
fornix, stria terminalis, VAFP, MMTT
amygdala projects to this through substantia innominata for stimulation of cortex for arousal and alterness
basal nucleus
white matter tract from subiculum and hippocampaus…leads into fimbria, which is beginning of fornix
alveus
NT for septal nuclei and nucleus accumbens
Ach
damage of ‘what’ pathway in Kluver Bucy syndrome will cause this
psychic blindness
chief output nucleus of amygdala; what is major input to this group?
central; hypothalamus and brainstem
what layer of neocortex is polymorphic layer of hippocampal cortex continuous with?
layer 6
outputs of papez circuit
neocortex and RF (influencing autonomic function)
this part of limbic system is involved in euphoria with cocaine and amphetamine use (act on dopamine from VTA, dopamine uptake, increase release), also mechanism of reward
nucleus accumbens
amygdala projects here to get info to cortex for perception of emotion
mediodorsal thalamus
where does stria terminalis project from amygdala?
basal nucleus, accumbens nucleus (motivated behavior), septal nuclei (motivated behavior), anterior hypothalamus
layer of hippocampal cortex that is susceptible to ischemia
pyramidal
layers of hippocampal cortex
molecular, pyramidal, polymorphic
what is major input to corticomedial group in amygdala?
olfactory piriform cortex, hypothalamus, thalamus
this is involved in *Sommer’s sector*…vulnerable to anoxia (near drowning, MI), difficulty learning new skills, related to epilepsy
CA-1 subiculum interface
inputs to nucleus accumbens
amygdala, HF, ACC, bed nucleus of stria terminalis
receptors related to long-term potentiation
NMDA-type glutamate
what kind of info does perforant pathway
highly processed cortical info
two areas that HF projects to….postocmmisural column; precommisural column
mammillary nuclei and thalamic nuclei; septal nuclei, preoptic/periventricular area (hypothalamus), nucleus accumbens
nuclei in thalamus involved in limbic system
anterior and DM nuclei
where do basolateral group and corticomedial group of amygdala project?
central group
where do efferent projections from amygdala travel through to get to the mediodorsal thalamus, hypothalamus, and basal nucleus?
substantia innominata
how many layers does neocortex have? where is this found?
6; primary sensory, motor, association cortex
fiber bundle formed from alveus and continuous with fornix
fimbria
primary neuron in hippocampus and subiculum
pyramidal
basis for memory…long-term synaptic efficacy/stimulation (first seen in Schaffer collaterals)
long term potentiation
blood supply to parahippocampal gyrus (what branch?) and uncus (what branch)?
PCA (temporal br, mostly uncal br. of MCA)
entorhinal cortex receives majority of afferents to HF from these brodmann areas
19, 22, 7
most afferent fibers of limbic system terminate here; where do these cells then project?
granule cells dentate gyrus; dendrites pyramidal cells CA3 (via mossy fibers)
transitional to 6 layered neocortex in hippocampal formation…continuous with parahippocampal formation
subiculum
how many layers does archicortex have? where is it found?
3; dentate gyrus and hippocampus
septal nuclei, nucleus accumbens receive big input from this structure for award center
ventral tegmental tract (dopamine)
major group in amygdala in humans; what is input here?
basolateral; orbital and prefrontal cortex, thalamus, insular and parahippocampus cortices
lesion of hippocampus will cause this (or really most things in Papez circuit)
anterograde amnesia
inputs to papez circuit
neocortex, thalamus, septal areas, raphe nuclei, VTA, catecholaminergic RF
damage to these structures seen in Korsakoff syndrome
mammillary bodies, DM thalamus, fornix
