Can’t Handle the Stress? Blame your Brain
Do you rise to the occasion, or do you fold under the pressure? No matter which side of the fence you’re, you can thank [or blame] your brain. Some people can deal with stressful situations better than others, and while you might suspect it is genetic, even identical twins show differences in how they respond.
But fear not, researchers have identified a specific electrical pattern in the brains of genetically identical mice that predicts how well individual animals will fare in stressful situations.
The findings will hopefully help researchers find ways to prevent potential consequences of chronic stress — from conditions like post-traumatic stress disorder, depression and other psychiatric disorders.
“In soldiers, we have this dramatic, major stress exposure, and in some individuals it’s leading to major issues, such as problems sleeping or being around other people,” said senior author Kafui Dzirasa, M.D., Ph.D. “If we can find that common trigger or common pathway and tune it, we may be able to prevent the emergence of a range of mental illnesses down the line.”
In the new study, the team analyzed the interaction between two interconnected brain areas that the control fear and the stress responses in both mice and men [for those who love the brain, this would be the prefrontal cortex and the amygdala]. The amygdala , for those interested, plays a role in the ‘fight-or-flight’ response. The prefrontal cortex on the other hand is involved in planning and other higher-level functions. It helps suppresses the amygdala’s reactivity to danger and helps people continue to function in stressful situations.
Implanting electrodes into the brains of the mice then allowed the researchers to “listen in” on the tempo [or reactivity] at which the prefrontal cortex and the amygdala were firing, this would also allow researchers to determine how tightly the two areas were linked — the ultimate goal of the monitoring was whether the electrical pattern of cross talk could help decide how well animals would respond when faced with an acute stressor.
What the researchers found was, in mice that had been subjected to a chronically stressful situation [which was daily exposure to an aggressive male mouse for about two weeks] the degree to which the prefrontal cortex seemed to control amygdala activity. This was in turn related to how well the animals coped with the stress, the group found.
Then the group looked at how the brain reacted to the first instance of stress, or at the times before the mice were put in a chronically stressful situation. The mice more sensitive to chronic stress showed greater activation of their prefrontal cortex-amygdala circuit, compared with resilient mice.
“We were really both surprised and excited to find that this signature was present in the animals before they were chronically stressed,” Dzirasa said. “You can find this signature the very first time they were ever exposed to this aggressive dangerous experience.”
Dzirasa hopes to use the signatures to come up with potential treatments for chronic stress. “If we pair the signatures and treatments together, can we prevent symptoms from emerging, even when an animal is stressed? That’s the first question,” he said.
In the long term, the group also hopes to delve further into the brain. They want to see whether the circuit-level patterns can interact with genetic variations that confer risk for psychiatric disorders [things like schizophrenia]. For now, thanks to this new study researchers will be able to segregate stress-susceptible and resilient animals before they are subjected to stress and look at their molecular, cellular and systemic differences.
Even if the work only helped find a way to help people with PTSD, or other chronic stress problems, it would be an amazing find.
Already feeling the pressure? Think you can handle the full study? You can find it –here!
Kumar, S., Hultman, R., Hughes, D., Michel, N., Katz, B., & Dzirasa, K. (2014). Prefrontal cortex reactivity underlies trait vulnerability to chronic social defeat stress Nature Communications, 5 DOI: 10.1038/ncomms5537