Limbic System Flashcards

1
Q

describe the limbic system in a nutshell

A
  • emotionally significant stimuli activate sensory pathways that trigger HYPOTHALAMUS to modulate HR, BP, respiration (cahnges accompanying emotional response)
  • info about emotionally significant stimuli also conveyed to CEREBRAL CORTEX, to integrate MOTOR RESPONSES to stimuli
  • process of MEMORY and LEARNING is integrated into the system
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2
Q

What major parts of the brain are associated with the limbic system?

A
  • hippocampal formation (hippocampus, fornix, dentate gyrus)
  • amygdala
  • hypothalamus
  • cingulate gyrus
  • anterior, lateral dorsal, and dorsal medial nuclei of thalamus
  • limbi association cortices
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3
Q

function of amygdala

A
  • formation and storage of info related to emotional events (long-term memory formation)
  • help us recognize when we are in danger or fearful of something
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4
Q

lesion to amygdala

A
  • become docile
  • affect memory formation, emotional sensitivity, learning and retention
  • depression and anxiety
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5
Q

input and output of limbic system

A
  • input: entorhinal cortex projects to dentate gyrus via perforant pathway , synapsing on granule cells
  • output: granule cells –> CA3 pyramidal neurons –> Sheaffer collaterals –> CA1

(note: CA1 cells give rise to fornix)

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6
Q

Where is the limbic association cortex?

A

medial surface of frontal, parietal, temporal lobes (mesolimbic structures)

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7
Q

Which gyri are part of the limbic association cortex?

A
  • orbitofrontal gyrus
  • paraterminal gyrus
  • subcallosal gyrus
  • cingulate gyrus
  • parahippocampal gyrus
  • temporal pole (entorhinal cortex)
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8
Q

Which structures are involved in the circuit of Papez that regulates emotion?

A
  • hypothalamus with mamillary body
  • anterior thalamic nucleus
  • cingulate gyrus
  • hippocampus
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9
Q

Describe and draw the Circuit of Papez. note the reciprocal step

A

1) cortex <–> CINGULATE GYRUS (RECIPROCAL)
2) cingulate gyrus –> hippocampal formation (via cingulum)
3) hippocampal formation –> hypothalamus with mamillary body (via fornix)
4) hypothalamus/mam. body –> anterior thalamic nuclei (via M-T tract)
5) anterior thalamic nuclei –> CINGULATE GYRUS
6) CINGULATE GYRUS –> cortex

REPEAT

KEY: reciprocal between cortex and cingulate gyrus

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10
Q

Describe and draw the Circuit of Maclean (current theory). note the reciprocal step

A

1) PFC/Association Cortex –> cingulate gyrus/hippocampal formation
2) Association cortex <–> hippocampal formation –> amygdala (RECIPROCAL)
3) hippocampal formation/amygdala –> hypothalamus/mam. body (via fornix)
4) hypothalamus/mam. body –> PFC/association cortex

REPEAT (note: NO anterior thalamic nuclei; addition of amygdala)

KEY: reciprocal between hippocampus and association cortex/PFC

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11
Q

if left hippocampus damaged?

A

auditory/vocal memory loss

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12
Q

if both hippocampi removed?

A

anterograde amnesia

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13
Q

TRUE or FALSE: hippocampus has a direct role in emotion

A

FALSE –> indirect role in emotion; direct role in explicit/declarative memory, memory consolidation and learning from emotional experiences

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14
Q

Which part of the limbic system is most specifically involved with emotional experience?

A

amygdala

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15
Q

What is the lateral amygdala linked to? what is its main function?

A
  • linked to neocortex
  • stimulate = fear –> anxiety
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16
Q

What is the medial amygdala linked to? what is its main function?

A
  • linked to striatum
  • connects motor and brainstem
17
Q

What structure connects the 2 amygdalae?

A

anterior commissure

18
Q

lateral hypothalamus function vs ventromedial hypothalamus?

A
  • lateral hypothalamus = pleasure center
  • ventromedial hypothalamus = aversion (satiety) center
19
Q

which 2 nuclei make up the reward centre of the brain?

A
  • septal nuclei
  • nucleus accumbens
20
Q

bilateral lesion to frontal gyri

A

apathy; indecisiveness; difficulty concentrating

21
Q

bilateral lesion to orbital cortex

A

unstable emotional behaviour; loss of inhibition; inappropriate social behaviour

22
Q

bilateral lesion to temporal pole (entorhinal cortex)

A

fearlessness

23
Q

bilateral lesion to parahippocampal gyrus

A

anterograde amnesia

24
Q

basic game plan of the limbic system? main role of amygdala? main role of hippocampus?

A

cortex –> LAC –> amygdala/hippocampus –> cortex

  • amygdala: link stimuli with emotion –> object recognition –> PROGRAM AND ORGANIZE RESPONSE TO POTENTIAL THREAT
  • hippocampus: reflect more complex features of environment –> spatial relationships –> LEARN AND REMEMBER
25
Q

2 efferent pathways of the amygdala?

A
  • ventral amygdalofugal path to: 1) thalamus, 2) hypothalamus, 3) rostral cingulate gyrus and orbitofrontal cortex and septal nuclei –> CONSCIOUS PERCEPTION OF EMOTION (pleasure and reward centre)
  • stria terminalus path to: 1) hypothalamus, 2) nucellus accumbens (euphoria) –> MOTOR PLANNING
26
Q

What is damaged in Korsakoff’s Psychosis? What is the result?

A
  • anterograde amnesia
  • damage to hippocampi, MD nucleus of thalamus, mamillary bodies
27
Q

4 major NTs delivered to limbic areas?

A
  • dopamine
  • serotonin
  • norepinephrine
  • acetylcholine
28
Q

Describe midbrain dopaminergic projections.

A
  • from: midbrain (VTA) and SNc
  • via: medial forebrain bundle
  • to: limbic areas
29
Q

what disease is mimicked when there is an increase in dopamine?

A

schizophrenia

30
Q

What is the hypothesis behind schizophrenia?

A

increased dopamine response in nucleus accumbens –> PFC dysfunction

31
Q

Describe ascending serotonergic projections.

A
  • from: reticular formation (raphe nuclei)
  • via: medial forebrain bundle
  • to: limbic areas, striatum and cerebral cortex
32
Q

Describe noradrenergic projections.

A
  • from: locus coeruleus
  • via: medial forebrain bundle
  • to: limbic system, entire cerebral cortex
33
Q

Describe basal forebrain cholinergic projections.

A
  • from: basal forebrain cholinergic neurons (incl. Nucleus Accumbens, Septal Nuclei)
  • via: diverse pathways
  • to: limbic system, cerebral cortex
34
Q

degeneration of which neurons begins Alzheimer’s Disease?

A

cholinergic neurons