Hypothalamus and limbic system

Question 1

Limbic system

Answer 1

a collection of cortical and subcortical structures that regulate learning, memory, emotion, and executiev function
- involve hippocampus, entorhinal cortex, and frontal lobes, etc

Regulate emotion est understood by its results

• experience/feelings of emotional state
• expression of behaviours
• involve: amygdala, hypothalamus, frontal lobes

Question 2

Limbic lobe anatomy

Answer 2

ring of cortex on medial surface of the brain, spanning aspects of frontal, parietal, and temporal lobes

Question 3

Hippocampus anatomy

Answer 3

deep within temporal lobe
floor of inferior horn of lateral ventricle
curved sheet of cortex folded in on itself

Question 4

Amygdala anatomy

Answer 4

rostal/anterior and medial to hippocampus

deep to the uncus

Question 5

Hippocampus fxn

Answer 5

learning
memory function & retrieval
site of adult neurogenesis

Question 6

Amygdala function

Answer 6

emotional learning & memory
fear
reward

Question 7

Memory classifications

Answer 7

Short Term

Long term
Declarative: episodic/semantic
Nondeclarative

Question 8

Hippocampus ascending output

Answer 8

entorhinal cortex
association areas (temporal, insular)

Question 9

Hippocampus descending output

Answer 9

Fimbria-fornix

Mamillary body: anterior thalamus (mamillo-thalamic tract), Raphe (mammillo-tegmental tract)

Hypothalamus: behaviour, autonomic, endocrine function

Send information back up to areas of cortex to further modulate memory storage and behavioural output

Question 10

Hippocampus input

Answer 10

Amygdala: basolateral (BLA), sensory part)

Sensory association areas: temporal lobe, insular cortex

Entorhinal area (via the cingulum): anterior thalamus, medial prefrontal/orbital cortex

Allowing to-down cortical control of emotional responses

Question 11

Amygdala nuclei

Answer 11

Medial (MeA)
Basolateral (BLA)
Central (CeA)

Question 12

Medial nucleus of amygdala

Answer 12

output to hypothalamus

regulates social behaviour

Question 13

Basolateral nucleus of amygdala

Answer 13

BLA
Outputs to cortex, hippocampus, hypothalamus
Integrates sensory information

Question 14

Central nucleus of amygdala

Answer 14

CeA
Outputs to hypothalamus (PVN = cortisol), frontal cortex, brainstem (adrenaline)
- mediate fight/flight, including subjective, physiological changes in emotional state
- can also regulate cortisol and reticular, medullary, and brainstem responses

Question 15

Hypothalamus cell groups

Answer 15

Medial Preoptic
Suprachiastmatic
Supraoptic
Dorsomedial
Ventromedial
Arcuate Nucleus
Mammillary bodies
Paraventricular nucleus

Question 16

Paraventricular nucleus fxn

Answer 16

PVN
Regulates release of cortisol from adrenal gland
Mediated by HPA axis
Cortisol (lipophilic) is highly catabolic, and can access almost every cell in the body, including limbic system (largest # of GC receptors in the body)

Question 17

Acute consequences of cortisol elevation

Answer 17

adaptive
mobilize energy
increased vascular tone
suppress digestion
suppress reproduction
immune suppression
sharpen cognition

Question 18

Chronic consequences of cortisol elevation

Answer 18

Maladaptive
myopathy, diabetes
hypertension
ulceration
amennorhea, impotence
increased disease risk
neuron death

Question 19

First response (emotional)

Answer 19

Thalamus –> Amygdala activated and induces arousal, adrenaline, HR, and BP
Also stimulates PVN to increase cortisol in circulation

Question 20

Higher reasoning (emotional)

Answer 20

careful appraisal by sensory and frontal cortices dampen amygdala’s reaction
Logic prevails
Panic is removed, cortisol levels return to normal

Question 21

Misguided fear

Answer 21

IF logic fails:
amygdala continues to arouse, cause fear/ panic
Chronic elevation in cortisol can lead to a myriad of disorders