Topic 11 Flashcards
What’s the difference between active and passive coping responses? Which is usually associated with better stress resilience? If you have behavioral control over a stressor, would this be considered an active or passive coping response?
Passive coping responses include denial, behavioral & mental disengagement/withdrawal, and avoidance of the stressor (see title slide) in order to reduce the negative emotion associated with the stressor. They are generally not associated with stress resilience.
Active coping responses include active strategies focused on solving or mitigating the problem, rather than reducing the emotional consequences. They are associated with stress resilience.
Behavioral control is considered to be an active coping response.
A lack of control is aversive in adults. Which experiment provided evidence that this aversion is likely innate, rather than learned?
The desire for control may reflect a fundamental & biological need and is present very early in development. As early as 4 months old, babies show negative emotional reactions in response to a loss of control.
For example, when there was a disruption of a learned contingency between behavior (reaching with an arm) and a reward (presentation of a colorful slide + music for 3 seconds), babies showed increased facial expressions of anger even when the reward was still presented, but was not contingent on the action.
What is learned helplessness? Do you see this behavior in people or animals or both?
Inescapable (uncontrollable) stress can lead to learned helplessness. Learned helplessness is a learned behavior in people and animals, arising after an aversive experience, where the organism fails to avoid a subsequent aversive experience, even though it is escapable. In people, learned helplessness is a psychological state characterized by reduced motivation, difficulty in determining causality, and depressed mood.
Both
Having behavioral control over a stressor prevents learned helplessness. Could you describe the experimental set-up that Steve Maier’s lab uses to give rats inescapable versus escapable tailshock stress? What does it mean to be yoked? What does it mean to be yolked? What are the 3 groups traditionally used? How are these groups similar to each other? How are they different from each other?
Experimentally, in rats, how can we investigate the effects of having behavioral control over a stressor?
Group 1: Control: Placed in apparatus, restraint but no shock
Group 2: Escapable Stress (ES): Restraint/tail shock + active wheel to control tail shock termination
Group 3: Inescapable Stress (IS): identical tail shock as ES, but inactive wheel - spins, but does not turn off shock
Important: Rats in the Escapable Stress (ES) and Inescapable Stress (IS) groups are YOKED in pairs, so they receive exactly the same physical stress. When the rat in the escapable stress (ES) group turns the wheel, it turns off the shock for both itself AND its yoked inescapable stress (IS) “partner”. IS and ES groups receive the SAME physical stressor exposure, but one has control, but the other does not.
How is learned helplessness typically assessed in rats? Would learned helplessness be indicated by a higher or lower escape latency? What does escape latency refer to in this test i.e. what do you measure to get an escape latency value? How would escape latencies differ in rats that had inescapable vs escapable stressor exposure 24 hours earlier?
One way to show learned helpless behavior in rats is by testing escape behavior in a shuttle box at some point (typically 24h) after IS.
Learned helplessness would be indicated by a higher latency escape time.
On the shuttle box test day, rats can escape a mild foot shock by “shuttling” from one side of the box to the other and back again. The latency to escape is measured.
In the social exploration of a juvenile test, would you expect social exploration to increase or decrease after exposure to inescapable tailshock stress? How about escapable tail shock stress?
Decrease
No effect
If you give a rat 2 foot shocks, it will freeze. Would you expect this freezing response to increase or decrease after exposure to inescapable tailshock stress? How about escapable tail shock stress? How is an increase in freezing response interpreted? (i.e. is it an increase in learned helplessness, anxiety, fear?)
Increases
ES does not produce a difference
Fear
What is Fos? Compared to a no-stress condition, would inescapable stress increase or decrease Fos in the dorsal raphe? Which neurotransmitter would also be contained in these cells? We didn’t see data for this, but for escapable stress, would you expect an increase in Fos in any other cell type in the DRN?
Fos is an early activation gene indicative of activation
IS increases Fos expression
serotonin
Dorsomedial striatum
Why would inescapable stress increase serotonin in the dorsal raphe nucleus (DRN)? Which technique could be used to measure that? In which other brain area(s) would you expect to see increased serotonin after inescapable stress? Would you expect any changes in serotonin (either basally or in response to stress) in DRN projection areas 24 hours later?
IS results in sensitization of serotonin neurons in the brainstem DRN.
You could measure this using microdialysis
5HT increases in the basolateral amygdala during and after IS
Basal Levels of Serotonin in the DRN are higher 24 hours after IS compared with ES
More 5HT is released after another stress following IS compared to ES.
If you wanted to show the DRN is necessary for the behavioral effects of IS, what could you do? If you wanted to show activation of the DRN is sufficient to produce similar behavioral effects as IS, what could you do?
You could lesion it or inactivate it with muscimol
You could activate it with a drug such as a benzodiazepine inverse agonist
How does the HPA axis response to IS vs ES compare? If IS and ES rats are subjected to another stressor 24 hours later, such as 5 footshocks, how would the HPA axis response compare?
They are the same.
They are similar
Which cortical region is thought to be critical for the effect of behavioral control in male rats? Which neurons in the DRN do projections from this region synapse with? Do these cortex to DRN projections excite or inhibit these DRN neurons? Does this increase or decrease sensitization of serotonin neurons of the DRN?
mvPFC
They are glutamatergic neurons that synapse with GABAergic neurons
These projections inhibit DRN neurons
Decrease
If you wanted to test the necessity of the PFC for the effects of behavioral control at the time of the stressor, rather than the effects of the PFC at the time of the behavioral test, what would you do?
You could inhibit it with muscimol at the time of the stressor. This will produce a temporary inactivation that will come back online at the time of the behavioral assessment.
If you inactivate the PFC during IS, what changes would you expect to see, compared to a rat with an active PFC during IS.
Inactivation of mvPFC has no effect of IS on serotonin release in the DRN
If you inactivate the vmPFC during ES, what changes would you expect to see, compared to a rat with an active vmPFC during ES.
vmPFC is Necessary for Control to Prevent Enhanced Release of Serotonin in the DRN after Intense Stress
But, inactivation of the vmPFC prior to ES makes the pattern of serotonin release in the DRN look like IS
