Limbic System

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What are the gyri/cortices included in the limbic system?

cingulate gyrus, parahippocampal gyrus, medial orbitofrontal cortex, and entorhinal cortex

What are the nuclei of the limbic system?

amygdala, hippocampus, septal nuclei, thalamus/hypothalamus, mammillary bodies, nucleus accumbens

what are the connections of the limbic system?

fornix, mammillothalamic tract, cingulum, and the medial forebrain bundle

the ___ is located near the temporal pole. it receives projections from the olfactory system and the temporal cortex, and has reciprocal connections with the septum.

amygdala

the hippocampal formation is made up of

the hippocampus, dentate gyrus, and parahippocampal gyrus

the ___ receives fibers from the entorhinal cortex and projects via the fornix to the mammillary body of the hypothalamus

hippocampal formation

the principle components of the limbic system are interconnected in the

Papez circuit

list the parts of the papez circuit, starting from the hippocampus

hippocampus → through fornix → mammillary body → through mammillothalamic tract → anterior nucleus → through internal capsule → cingulate gyrus → through cingulum → parahippocampal gyrus → entorhinal cortex → through perforant pathway → back to hippocampus

what are the interlocking C shapes of the hippocampal formation

CA1-CA3 of the hippocampus and the dentate gyrus

what are the segments of the hippocampal formation?

subiculum, CA1, CA2, CA3, CA4, dentate gyrus

input to the entorhinal cortex from the amygdala goes through what pathway?

the amygdalofugal pathway

from what point(s) does the hippocampus receive information?

information goes to the subiculum directly, or to the entorhinal cortex before the subiculum

what are the two outputs from the hippocampus?

back to subiculum, then to the cortex

to fornix, to subcortical areas

the ___ converge in the midline to become the fornix

fimbriae

on the anterior end of the fornix, there are split ends. what are they?

anterior to the anterior commissure are the precommissural branches of the fornix. they go to the septum.

posterior to the anterior commissure are the postcommissural branches that go to the mammillary bodies

memory loss (profound anterograde amnesia, some retrograde) caused by lack of thiamine, especially in chronic alcoholics. they may confabulate (fill a gap in memory with falsification)

Korsakoff’s syndrome

Korsakoff’s syndrome is a lesion to the

mammillary bodies

the cingulate gyrus has inputs from

anterior nucleus of thalamus and the frontal, somatosensory, and visual cortices

what are the functions of the cingulate gyrus?

emotion processing, learning, emotional memory, attention flexibility, empathy

involved in anger and fear recognition

amygdala

the amygdala projects to the ___

cerebral cortex and hypothalamus

the amygdalae send impulses to the hypothalamus for important activation of the ___ nervous system

sympathetic

the amygdalae send impulses to the reticular nucleus for ___

increased reflexes

the amygdalae send impulses to the trigeminal nerve and facial nerve for ___

facial expressions of fear

the amygdalae send impulses to the ___ for the activation of dopamine, norepinephrine, and epinephrine

ventral tegmental area, locus coeruleus, and the laterodorsal tegmental nucleus

the centromedial nuclei are the main outputs for the basolateral complexes, and are involved in ___

emotional arousal

what nuclei serve as a relay of hippocampus to the hypothalamus?

the septal nuclei

emotional memory and rage are associated with the ___

septal nuclei

the ventral striatum and the ___ are the same

nucleus accombens

where is the nucleus accumbens?

where the caudate and putamen meet

the nucleus accumbens is important for ___

reward and pleasure

projections from the VTA to the nucleus accumbens go through the

medial forebrain bundle

overall, what are the functions of the limbic system?

fight/flight, fear and emotions, memory, sexual behavior

Klein-Levin syndrome

hypothalamic hamartoma. recurring episodes of severe sleepiness, accompanied by behavioral changes, such as sexual aggressiveness, hyperphagia, hallucinations, excessive hunger.

Kluver Bucy syndrome

memory loss, hypersexuality, excessive hunger, chewing, flattened affect

lung carcinoma can be associated with

limbic encephalitis

limbic encephalitis symptoms

seizures, apathy, confusion, short-term memory difficulty, sexual disinhibition, episodic agitation, emotional lability, disorientation. gradual onset

what is abulia?

decreased motivation/drive to perform actions necessary for taking care of oneself, communicating, etc. no motor issues, but not moving, speaking, using the restroom on their own, etc. associated with frontal lobe damage

how are the voluntary and spontaneous smile circuits different?

the spontaneous smile circuit involves the limbic system and only involves the direct pathway.

the voluntary smile circuit involves the motor cortex and both indirect and direct pathways.

if someone’s basal ganglia is not damaged by a stroke, the ___ circuit is intact

spontaneous smile circuit