-
Try to describe stress, allostasis, and allostatic load with a thermostat example
- Inside temp
- Outside temperature perturbation
- Sensed temp change and error signal = stress
- Thermostat setting = allostasis
- Signal to furnace to turn
- But furnace wear and tear = allostatic load
-
What is the hypothesis for allostatic load?
Some subjects may not readily show habituation of adrenocortical stress responses to repeated psychological stress
-
What are the 4 ways cortisol levels can be measured?
-
How quick can you measure cortisol level with blood?
Minutes
-
How quick can you measure cortisol levels with saliva?
Minutes
-
How quick can you measure cortisol levels with fecal matter?
Hours
-
How quick can you measure cortisol levels with hair?
Weeks
-
What's the best proxy for measuring cortisol levels?
- Blood
- Can be from diff environments
-
What's a good proxy for what's happening in the blood in terms of cortisol levels?
Saliva
-
On a graph measuring cort levels, what is represented by the curve and what is represented by the area under the curve
- Curve- cort levels from blood
- Under curve- fecal measurement of cort levels
-
Why is fecal matter not the best indicator of cort levels at a certain moment?
- Don't see rise and fall
- Only what happened over the last 12 hours
-
What was wrong with the experiment done to test the hypothesis of whether subjects show habituation of stress responses to repeated psychological stress?
- All male- didn't show gender diffs
- Self-reporting
- Particular group of people- homogenous
- Small sample size
- Exclusion criteria
- Ran experiment in very specific time point
-
What was the cortisol responses to the public speaking and mental arthmetic task?
- High on first day
- Still high but consistant for the following days
-
What were some correlations found in the public speaking and mental arithmetic task experiment?
- Mean cortisol response was correlated with personality traits
- Correlations observed btwn mean cortisol response and self concept of competence, social resonance, trustfulness
-
What 2 kinds of responders were there in the public speaking and arithmetic experiment?
- High responders
- Low responders
-
What did high responders show in the public speaking and arithmetic experiment?
- High response on first day
- But didn't really adapt after that
-
What did low responders show in the public speaking and arithmetic experiment?
- Didn't have as high a response as high responders
- Also went back to normal/baseline for following days
-
Other than their cortisol levels, what were differences btwn high and low responders to stress in the public speaking and arithmetic experiment?
- High responders- Saw themselves as less attractive, less self-esteem, more often depressed
- Low responders- Saw less of these symptoms
-
What are the 4 major characteristics of cortisol secretion in normal subjects?
- Pulsatile secretion
- Circadian rhythm
- Stress-induced secretion
- Negative feedback inhibition by GCs
-
What is pulsatile secretion?
- Ultradian pulsatility
- Ultradian rhythms are recurrent periods or cycles repeated throught a 24 hr circadian day
-
What are circadian rhythms?
- Changes that follow an endogenous 24 hr cycle
- Responds primarily to light and darkness
-
What hormone is a big player for the rhythm/clock in our body?
Cortisol
-
What do cortisol levels look like in relation to the circadian rhythm?
- Low but slowly rising during sleep period
- Peak right before and after waking up
- Goes up and down throughout the day
- Decreases at end of awake period
-
What is considered your "central clock"?
SCN
-
What are the 3 things the SCN affects?
-
What are the behaviors that the SCN affects/has control over?
- Wake/sleep
- Feeding/fasting
-
What are the 3 downstream things that are affected by the SCN?
- Feeding hormones
- Metabolites
- Body temp
-
What is the ultimate thing that the SCN is controlling?
Peripheral clocks (organs)
-
How does the SCN control the HPA axis?
- SCN receives light
- Sends output to diff brain areas
- SCN -> Creation of dinural oscillation -> PVN in hypothalamus
- PVN controls HPA axis
- Adrenal gland secretes GC that's time sensitive
-
During the day, sensitivity to which hormone in the adrenal gland changes?
ACTH
-
What is StAR?
- A rate-limiting gene of steroid biosynthesis
- Directly controlled by the clock: BMAL1 heterodimer
-
How were cortisol levels in aged mammals studied?
- Aged baboons
- Studied dynamics of social structures
-
What was found when studying cortisol levels in aged baboons?
They have elevated cort levels
-
How is the stress response increased during aging?
- NEp/Ep responses are increased
- Basal cortisol levels are increased
- Stress responses last longer
-
How did cold stressor affect body temperature in 20 year old vs. 80 yr old?
- 20- Dip in temperature but immediately went back to normal
- 80- Dip in temperature but took longer to go back to normal
-
How did time pressure stressor affect performance on IQ test for 20 yr old vs. 80 yr. old?
80 yr old performance declined quicker than 20 year old
-
What other causes are there for cort levels being high?
- Individual variability
- Correlation btwn hippocampal volume, cort levels and cognitive performance
|
|
