SM_89b: Limbic System Flashcards
List components of the limbic system
Components of the limbic system
- Limbic lobe: ring of cortex outside of corpus callosum - parahippocampal, cingulate, subcallosal gyri
- Amygdala
- Hippocampal formation and associated structures
- ± olfactory (piriform cortex)
- ± hypothalamus (mamillary bodies) ± parts of thalamus connected above
Describe organization of limbic cortex
- Hippocampal formation (limbic core, 3 layers, archicortex)
- Paralimbic cortex (transitional cortex, 6 layers, mesocortex)
or (allocortex, paleocortex, archicortex)
Limb cortices ____ have the 5-6 layered structure of the rest of the cerebral cortex (neocortex)
Limb cortices do NOT 5-6 layered structure of the rest of the cerebral cortex (neocortex)
Limbic cortex forms a ____
Limbic cortex forms a ringlike limbic lobe around the edge of the cortical mantle, which surrounds the corpus callosum and upper brainstem
Functions of the limbic system are ____, ____, ____, and ____
Functions of the limbic system are homeostatic functions including autonomic and neuroendocrine control, olfaction, memory, and emotions / drives
Paralimbic cortex serves as a ____
Paralimbic cortex serves as a mediator between association cortex and limbic system
Describe the paralimbic cortex pathway
Paralimbic cortex pathway
- Cingulate gyrus
- Paraolfactory cortex
- Orbitofrontal cortex
- Insula
- Uncus
- Parahippocampal gyrus
- Cingulate gyrus
Hippocampal formation is ____ containing the ____, ____, and ____ submerged deep in the ____
Hippocampal formation is primitive cortical structure containing the dentate gyrus, hippocampus, and subiculum submerged deep in the parahippocampal gyrus
Describe the pathway of the hippocampal formation
Hippocampal formation
- Cortex
- Entorhinal cortex (medial temporal lobe)
- Perforant pathways
- Dentate gyrus (input station)
- Hippocampus
Hippocampus extends the length of the floor of the ____ and becomes continuous with the ____ below the splenium of the corpus callosum
Hippocampus extends the length of the floor of the inferior horn of the lateral ventricle and becomes continuous with the fornix below the splenium of the corpus callosum
___ through ___ are sectors of the hippocampus
CA1 through CA4 are sectors of the hippocampus
(subiculum is the mesocortex from the 3rd-6th layers)
____ of the hippocampus is most susceptible to ischemia
Sommer sector (CA1 and CA2) of the hippocampus is most susceptible to ischemia
Describe hippocampal input and output
Hippocampal input and output
- Cortical areas
- Alvear pathways and perforant pathways
- Dentate / hippocampus
- Mossy fibers go to CA3
- Fornix
- Fibers bend around thalamus and axons terminate in the mamillary bodies of the hypothalamus or septal area / anterior thalamus
Papez circuit provides an anatomic substrate for convergence of ____, ____, and ____
Papez circuit provides an anatomic substrate for convergence of cognitive (cortical) activities, emotional experiences, and expression
(ties the cerebral cortex and hypothalamus)
Papez circuit consists of the ____, ____, ____, ____, and ____
Papez circuit consists of the parahippocampal gyrus, hippocampus, mamillary bodies, anterior thalamus, and cingulate gyrus
Describe pathway of the Papez circuit
Papez circuit
- Hippocampal axons to fornix
- To mamillary bodies
- Via mamillothalamic tract to anterior thalamus
- Cingulate gyrus
- Parahippocampal gyrus
Papez circuit ends in the ____
Papez circuit ends in the parahippocampal gyrus
Principal connections to limbic system include ____ and ____
Principal connections to limbic system include hippocampal system / limbic lobe and olfactory / amygdaloid connections
Describe connections between the amygdala and hypothalamus
Connections between the amygdala and hypothalamus
- Hippocampus to mamillary bodies of thalamus via fornix
- Amygdala to hypothalamus and vice versa via stria terminalis and amygdalofugal pathway
- Cingulate gyrus to hypothalamus via medial forebrain bundle
Lesions in lateral amygdala induce ____
Lesions in lateral amygdala induce unrestrained eating (bulimia)
Lesions in medial amygdala induce ____ and ____
Lesions in medial amygdala induce anorexia and hypersexuality
Electrical stimulation of amygdala results in ___, ___, ___, and ___
Electrical stimulation of amygdala results in fear, anxiety, rage, and aggression
Hippocampus converts ____ to ____ and contains ____ that encode ____
Hippocampus converts short-term memory to long-term memory and contains place cells that encode spatial memory
Bilateral damage to hippocampus / fornices can cause ____
Bilateral damage to hippocampus / fornices can cause anterograde amnesia (no new memories can be formed)
Alzheimer’s disease commonly results from degeneration in parts of the ____
Alzheimer’s disease commonly results from degeneration in parts of the Papez circuit
- Impaired
- Unable to learn new information
- Difficulty naming people, objects, etc
Transient global amnesia is a rare disorder involving ____ due to damage in the ____ and ____
Transient global amnesia is a rare disorder involving episodic memory problems due to damage in the hippocampus and other medial temporal lobe structures in the Papez circuit
Wernicke-Korsakoff results from ____ and commonly occurs in ____
Wernicke-Korsakoff results from thiamine/B1 deficiency and commonly occurs in alcoholics
Wernicke-Korsakoff results in triad of ____, ____, and ____ acutely
Wernicke-Korsakoff results in triad of ataxia, eye movement abnormalities (horizontal gaze paresis / nystagmus / ophthalmoplegia), and confusional states
(anterograde and retrograde amnesia after acute stage, poor judgement / initiative / impulse control / sequencing tasks, lack of awareness, confabulate when answering questions)
Wernicke-Korsakoff results from ____ necrosis of ____
Wernicke-Korsakoff results from bilateral necrosis of mamillary bodies
HSV-1 has tropism for the ____ and can cause ____
HSV-1 has tropism for the limbic cortex and can cause severe encephalitis involving predominantly the limbic areas
Limbic encephalitis is ____
Limbic encephalitis is autoimmune (inflammatory)
