Stress and Our Brain Response

Those cravings for cookies, chips, or other salty/sweet junk foods have a lot to say about how our brain regulates those urges under stress. It happens to the best of us: we are up long hours of the night craving something to eat, but our mind wanders to the bag of potato chips. Structures in our brain and studies done on those structures gives us a deeper understanding of how stress can affect these urges. Our ventral medial pre-frontal cortex (vmPFC) is a structure in our brain that is part of the pre-frontal cortex. Our vmPFC is the center to regulate our fear and our process of risk management. In addition, the vmPFC plays a huge role in inhibiting our emotions and our decision processing. Our vmPFC works very closely with another structure in our brain called the amygdala. The amygdala is a small structure in our brain that also plays a large role in processing fear. The amygdala is also part of the limbic system in our brain. The limbic system works in conjunction with the amygdala in order to regulate our emotions, memory, and our survival instincts.  In a research study done by Dr. Koenings, the vmPFC and the amygdala was studied in order to see whether or not they had an impact on the pathogenesis of anxiety and mood disorders. In addition, a study done by Silvia U, Aidan B. Makwana, and Todd A. Hare has studied the effects of self-control and goal-directed choices by studying the vmPFC and the amygdala, especially with late-night eating.

            In the study done by Dr. Koenings, four adults with bilateral parenchymal damage were studied. In these four adults, much of the damage was confined in the vmPFC making it easier to study the areas and the effects of the area in the brain. fMRI’s were conducted in order stimulate the amygdala. They would use the fMRI to track the adult’s response to aversive images. Each adult would either indicate an “X” for aversive, “O” for neutral responses, and “?” for no information/no response. MRIs were used to analyze aversive reactions as well. Also, heart rates in response to aversive images were measured and were linked back to amygdala activity and to activity in the vmPFC. According to the study, for each aversive picture, the groups exhibited “cardiac deceleration” in response to pictures that were aversive and/or neutral to the individual. It was found that vmPFC lesions with increased amygdala activity coordinated with the reactions to aversive pictures. These particular results are relevant to the models of emotional regulation and psychopathology. In addition, it was also found that damage to the vmPFC also resulted in personality changes that were correlated to psychopathy rather. Therefore, vmPFC and the amygdala are directly related to stress, anxiety, and depression.

            In the study done by Silvia U, Aidan B. Makwana, and Todd A., self-control was ultimately tested in individuals and the results of the study were also linked back to the vmPFC and the amygdala. For their study, fifty-one men were asked to rank 70 foods on the basis of “healthiness and tastiness.” Of the 51, 29 placed their hands in cold water in order to induce stress. fMRIs were used to monitor the stress levels of the individuals. While they were stressed, they are asked to indicate what they wished to eat. Of those 29 that experienced stress chose junk food over healthy foods, and the other 22 chose healthy foods over junk food. The fMRI images of these individuals found that the vmPFC was clogged due to the fact that the amygdala increased its stimulation. Therefore, with the overactive amygdala, the stressed individuals were more likely to make the less smart decision to eat the junk food over the healthy food. When individuals are stressed, the amygdala’s activity makes it harder for us to process our decisions.  In addition, their findings showed that stress “biases” the decision making process in the brain by altering two pathways: one pathway that signals information about the stimulus, such as taste and sound, and the other pathway is linked to goal maintenance. Stress led to a stronger taste attributes.

            When looking at these two studies of the human brain, it can be concluded that the amydgala and the vmPFC play an important role when distinguishing our responses to stress. In Dr. Koenings study, it was evident that a damaged vmPFC and amygdala can create responses that are not ideal. When looking at the aversive images, the brain would undergo stress and so would the heart. In Silvia U, Aidan B. Makwana, and Todd A’s study, stress would make individuals make decisions under poor judgment. Therefore, our vmPFC and amygdala play an important part in regulating our decision-making and our reaction to certain factors. So the next time you reach for those cookies, Cheetoes, or other junk foods late at night, know why your body is craving these and how you can regulate your stress by not doing so.

If you're craving cookies, this may be why. Plus a simple fix. (n.d.). Retrieved December 8, 2015, from http://www.today.com/health/craving-cookies-may-be-why-plus-simple-fix-t36961

Maier, S., Makwana, A., & Hare, T. (2015, August 5). Acute Stress Impairs Self-Control in Goal-Directed Choice by Altering Multiple Functional Connections within the Brain’s Decision Circuits. Retrieved December 8, 2015, from http://www.sciencedirect.com/science/article/pii/S0896627315006273

Motzkin, J., Philippi, C., Wolf, R., Baskaya, M., & Koenigs, M. (n.d.). Ventromedial Prefrontal Cortex Is Critical for the Regulation of Amygdala Activity in Humans. Biological Psychiatry, 276-284. http://dx.doi.org/10.1016/j.biopsych.2014.02.014