SM_89b: Limbic System Flashcards

1
Q

List components of the limbic system

A

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
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2
Q

Describe organization of limbic cortex

  • Hippocampal formation (limbic core, 3 layers, archicortex)
  • Paralimbic cortex (transitional cortex, 6 layers, mesocortex)

or (allocortex, paleocortex, archicortex)

A
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3
Q

Limb cortices ____ have the 5-6 layered structure of the rest of the cerebral cortex (neocortex)

A

Limb cortices do NOT 5-6 layered structure of the rest of the cerebral cortex (neocortex)

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4
Q

Limbic cortex forms a ____

A

Limbic cortex forms a ringlike limbic lobe around the edge of the cortical mantle, which surrounds the corpus callosum and upper brainstem

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5
Q

Functions of the limbic system are ____, ____, ____, and ____

A

Functions of the limbic system are homeostatic functions including autonomic and neuroendocrine control, olfaction, memory, and emotions / drives

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6
Q

Paralimbic cortex serves as a ____

A

Paralimbic cortex serves as a mediator between association cortex and limbic system

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7
Q

Describe the paralimbic cortex pathway

A

Paralimbic cortex pathway

  1. Cingulate gyrus
  2. Paraolfactory cortex
  3. Orbitofrontal cortex
  4. Insula
  5. Uncus
  6. Parahippocampal gyrus
  7. Cingulate gyrus
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8
Q

Hippocampal formation is ____ containing the ____, ____, and ____ submerged deep in the ____

A

Hippocampal formation is primitive cortical structure containing the dentate gyrus, hippocampus, and subiculum submerged deep in the parahippocampal gyrus

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9
Q

Describe the pathway of the hippocampal formation

A

Hippocampal formation

  1. Cortex
  2. Entorhinal cortex (medial temporal lobe)
  3. Perforant pathways
  4. Dentate gyrus (input station)
  5. Hippocampus
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10
Q

Hippocampus extends the length of the floor of the ____ and becomes continuous with the ____ below the splenium of the corpus callosum

A

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

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11
Q

___ through ___ are sectors of the hippocampus

A

CA1 through CA4 are sectors of the hippocampus

(subiculum is the mesocortex from the 3rd-6th layers)

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12
Q

____ of the hippocampus is most susceptible to ischemia

A

Sommer sector (CA1 and CA2) of the hippocampus is most susceptible to ischemia

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13
Q

Describe hippocampal input and output

A

Hippocampal input and output

  1. Cortical areas
  2. Alvear pathways and perforant pathways
  3. Dentate / hippocampus
  4. Mossy fibers go to CA3
  5. Fornix
  6. Fibers bend around thalamus and axons terminate in the mamillary bodies of the hypothalamus or septal area / anterior thalamus
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14
Q

Papez circuit provides an anatomic substrate for convergence of ____, ____, and ____

A

Papez circuit provides an anatomic substrate for convergence of cognitive (cortical) activities, emotional experiences, and expression

(ties the cerebral cortex and hypothalamus)

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15
Q

Papez circuit consists of the ____, ____, ____, ____, and ____

A

Papez circuit consists of the parahippocampal gyrus, hippocampus, mamillary bodies, anterior thalamus, and cingulate gyrus

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16
Q

Describe pathway of the Papez circuit

A

Papez circuit

  1. Hippocampal axons to fornix
  2. To mamillary bodies
  3. Via mamillothalamic tract to anterior thalamus
  4. Cingulate gyrus
  5. Parahippocampal gyrus
17
Q

Papez circuit ends in the ____

A

Papez circuit ends in the parahippocampal gyrus

18
Q

Principal connections to limbic system include ____ and ____

A

Principal connections to limbic system include hippocampal system / limbic lobe and olfactory / amygdaloid connections

19
Q

Describe connections between the amygdala and hypothalamus

A

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
20
Q

Lesions in lateral amygdala induce ____

A

Lesions in lateral amygdala induce unrestrained eating (bulimia)

21
Q

Lesions in medial amygdala induce ____ and ____

A

Lesions in medial amygdala induce anorexia and hypersexuality

22
Q

Electrical stimulation of amygdala results in ___, ___, ___, and ___

A

Electrical stimulation of amygdala results in fear, anxiety, rage, and aggression

23
Q

Hippocampus converts ____ to ____ and contains ____ that encode ____

A

Hippocampus converts short-term memory to long-term memory and contains place cells that encode spatial memory

24
Q

Bilateral damage to hippocampus / fornices can cause ____

A

Bilateral damage to hippocampus / fornices can cause anterograde amnesia (no new memories can be formed)

25
Q

Alzheimer’s disease commonly results from degeneration in parts of the ____

A

Alzheimer’s disease commonly results from degeneration in parts of the Papez circuit

  • Impaired
  • Unable to learn new information
  • Difficulty naming people, objects, etc
26
Q

Transient global amnesia is a rare disorder involving ____ due to damage in the ____ and ____

A

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

27
Q

Wernicke-Korsakoff results from ____ and commonly occurs in ____

A

Wernicke-Korsakoff results from thiamine/B1 deficiency and commonly occurs in alcoholics

28
Q

Wernicke-Korsakoff results in triad of ____, ____, and ____ acutely

A

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)

29
Q

Wernicke-Korsakoff results from ____ necrosis of ____

A

Wernicke-Korsakoff results from bilateral necrosis of mamillary bodies

30
Q

HSV-1 has tropism for the ____ and can cause ____

A

HSV-1 has tropism for the limbic cortex and can cause severe encephalitis involving predominantly the limbic areas

31
Q

Limbic encephalitis is ____

A

Limbic encephalitis is autoimmune (inflammatory)