Stress and brain response
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Introduction
In the study of stress and behavioral response to stress, three main parts of the brain are of interest. These parts are interconnected and influence each other in managing stress. The first part is the amygdala which is related to emotions, and it affects emotional behavior and motivation. The amygdala evaluates threatening situations and is responsible for fear generation (Goleman, 2006). The second area is the prefrontal cortex, made up of anterior cingulate cortex, medial frontal gyrus and hasa connection to the amygdala. The primary purpose of prefrontal cortex is extinction of fear (Lupien et al., 2009)
The main responsibility of the prefrontal cortex in a stressful situation is to neutralize fear and respond to the fear-causing situation adequately. The hippocampus is the part of the brain concerned with memory. During the process of fear conditioning, the hippocampus interacts with the amygdala in encoding emotional memories. Chronic stress damages the hippocampal cells and causes memory loss, while damage to amygdala leads to irregular emotions and inappropriate response to fear from a damaged prefrontal cortex.
Glucocorticoids used in the short term are essential in alerting an organism of an impending threat, and prepares it for flight or fight to fend off the threat ("The Mindful Self-Express", 2016). Long term exposure to glucocorticoids, like cortisol ,shrinks the brain neurons and impede their ability to send and receive information through branches known as dendrites (McEwen, & Gianaros, 2011). In chronic stressful conditions, the level of Glucocorticoids remains elevated for longer periods. Continuous Exposure to Glucocorticoids under stressful conditions causes shrinking of the hippocampus, thereby depriving it of its ability to form new memories. Post-traumatic stress disorders and long-term depression are responsible for significant hippocampus shrinkage.
Glucocorticoids also damage prefrontal cortex. In significant amounts of stress, the level of cortisol and other Glucocorticoids are elevated, leading to the reduction of neurons in the prefrontal cortex that is responsible for ability to solve problems, adopt, and regulate emotion, as well as impulse control. Major life stressors thus damage mood centers and increase the victim’s vulnerability to addiction.
Stress hormones affect the hippocampus via the adrenal steroids. The stress hormones cause the hippocampal neurons to retract, thereby causing a decrease in hippocampal-related functions of memory. While stress makes neurons in the hippocampus to shrink, it works in opposite fashion in the amygdala, where it makes neurons grow. This causes the aggressive response and fear related to the amygdala to increase. Therefore, stress increases attack by facilitating growth of neurons in amygdala ("The Rockefeller University" 2016).
Stress also remodels dendrites and contributes to the creation of new neurons in the dentate gyrus part of the hippocampus. The propagation of neuron stem cell in the adult brain carries on in the subventricular zone, supplying new neurons to the olfactory bulb, the neocortex, and the dentate gyrus. These cells are found in the subgranular are...