The Stress-Response
•Mobilization of energy
•Increased cardiovascular tone
•Suppression of digestion
•
•Suppression of growth
•Suppression of reproduction
•Enhancement of immune system
•Sharpening of cognition
The consequences of chronic stress
•Mobilization of energy………………………Fatigue, diabetes, muscle loss
•Increased cardiovascular tone…………….Hypertension, heart disease
•Suppression of digestion…………………..Stress ulcers
•
•Suppression of growth……………………..Stress dwarfism
•Suppression of reproduction………………Anovulation, erectile dysfunction
•Enhancement of immune system…………Immune suppression, accelerated
chromosomal aging of immune
cells
•Sharpening of cognition……………………Impaired memory and judgment
The consequences of chronic stress
•Mobilization of energy………………………Fatigue, diabetes, muscle loss
•Increased cardiovascular tone…………….Hypertension, heart disease
•Suppression of digestion…………………..Stress ulcers
•
•Suppression of growth……………………..Stress dwarfism
•Suppression of reproduction………………Anovulation, erectile dysfunction
•Enhancement of immune system…………Immune suppression
•Sharpening of cognition……………………Impaired memory and judgment
Stress effects on the hippocampus:
the realm of memory
Impaired synaptic plasticity
Atrophy of dendritic networks of
communication
Fewer new neurons
Dead neurons!
Decreased overall hippocampal
volume
Result:
Impaired formation and retrieval of
long-term memories
Effects of stress and GCs on fear and anxiety
Increased:
-post-shock freezing
-consolidation of fear conditioning
-cued & contextual fear memory
-resistance to fear extinction
-anxiety
Conrad, Fanselow, Korte, LeDoux,
McGaugh, Quirk, Roozendaal, Sandi
Effects of stress and GCs on the amygdala
Increased:
-synaptic excitability
-dendritic aborization
LeDoux, Vyas, Mitra, Chatterjee
Result:
More anxiety, faster fearconditioning, slower habituation
Combining hippocampal
and amygdaloid effects of
chronic stress:
Weakened conscious memories;
Exaggerated autonomic memories.
The effects of chronic stress in the
mesolimbic dopamine system
Depletion of dopamine
Piazza, Maccari, Le Moal
Result:
Loss of the capacity for pleasure:
DEPRESSION
The effects of stress in the frontal
cortex
Decreased connectivity in neural networks
by way of fewer dendritic branches and
spines
Recovery that produces a “different”
frontal cortex, cytoarchitecturally
Wellman, Radley, Morrison
Result:
Dumb-Ass decisions that seem
really insightful at the time you
make them
When does predictive information
help?
Latency until stressor
Immediate
No time to
plan coping
strategy
Helpful
Long in
future
The anticipatory
anxiety outweighs
the advantages
When does predictive information
help?
Likelihood of stressor
Extremely
Likely
You already
assume it
will happen
Helpful
Extremely
Unlikely
You’re not
worrying
about it
When does a sense of control help?
Severity of stressor
Mild
stressor
Helpful
Look how much worse
It could have been
Disastrous
stressor
Look how much better
It could have been
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DOPAMINE
Signal
Work
Reward
DOPAMINE
Signal
Work
Reward
DOPAMINE
100% ________
50% ---------
Signal
Work
Reward
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Day 1
1 pellet
Day 2
2 pellets
Day 3
2 pellets
1 pellet
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Ishi, last of the Southern Yahi Tribe in California,
forced to live in Anthropology Museum at Berkeley
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