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Thursday, December 21, 2006
Experience Sculpts Brain Circuitry to Build Resiliency to Stress
Rats Develop “Illusion of Control”.
It’s long been known that experiencing control over a stressor immunizes a rat from developing a depression-like syndrome when it later encounters stressors that it can’t control. Now, scientists funded by the National Institute of Mental Health (NIMH), part of the National Institutes of Health (NIH), have unraveled the workings of the brain circuitry that inoculates against such hard knocks — the circuitry of resilience.
Control not only activated the brain’s executive hub, the prefrontal cortex, but also altered it so that it later activated even when the stressor was not controllable. This activation turned off mood-regulating cells in the brainstem’s alarm center. The immunizing effect was so powerful that even a week later, when confronted with an uncontrollable stressor, the cells behaved as if the stressor was controllable and the rat was protected.
“It’s as if the original experience with control leads the animal to later have the illusion of control even when it’s absent, thereby producing resilience in the face of challenge,” explained NIMH grantee Steven Maier, Ph.D., University of Colorado. “The prefrontal cortex is necessary for processing information about the controllability of stressors as well as applying this information to regulate responses to subsequent stressors.”
A report on this first study exploring the neural mechanisms by which an initial experience with a controllable stressor can block the later behavioral effects of an uncontrollable stressor, by Maier, Jose Amat, Ph.D., and colleagues, appears in the December 20, 2006 issue of the Journal of Neuroscience.
“Lack of control over stressful life experiences has been implicated in mood and anxiety disorders,” noted NIMH Director Thomas Insel, M.D. “Understanding how the brain encodes the experience of control to protect against such adverse consequences should help us develop better treatments for these disorders.”
Rats exposed to uncontrollable stress develop a syndrome similar to depression and post traumatic stresss disorder (PTSD) in which they lose the ability to learn how to escape stressors and behave more fearfully.
Maier’s research team had last year reported that the NIMH website.
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