The stress response begins with our interpretation of events - our appraisals, our perceptions, our thoughts, all of which are different words for the same concept. For instance, if you call a close friend and don't get a return phone call after two days you could conclude that your friend is busy or didn't get the message. This thought process is unlikely to be experienced as stressful. If, on the other hand, you conclude that your friend hasn't returned the call because they no longer like you, this experience of rejection is likely to be stressful. This is an example of a social-emotional stress. The importance of interpretation on the impact of stress applies to all kinds of stressors including ones that have an environmental origin. If you hear a loud noise outside and conclude it is that old car back firing again, you would likely have a much less stressful reaction than if you conclude that the noise was a gun firing.
How we interpret or think about events is only part of the complex equation that defines human reactions to stress. The brain also plays a crucial role in the feedback between mind, body and brain.
The experience of stress is first experienced in an area of the brain called the amygdala. The amygdala is a small almond shaped structure located deep in the brain that is associated with stress, anxiety, fear and aggression. It is like an alarm bell that goes off in response to events that are interpreted as threatening thus initiating a cascade of events including:
The thalamus, a relay station for sensory information, sends a message to
the brain stem, which connects the brain and the spinal cord. The brain
stem then releases norepinephrine which then stimulates the brain and body
for flight or fight.
The activating part of the nervous system, the sympathetic branch, readies the
organs and muscles in the body for the fight or flight response (to with fight
off the threat or flee).
The hypothalamus, which regulates basic drives such as hunger and sex, signals
the pituitary gland to release adrenaline to rev up the body, and cortisol which
Now, the body is energized and ready for action - heart rate increases, pupils dilate, blood is directed to the large muscles, and lungs prepare for increased oxygen exchange. The increased cortisol magnifies the stress response by activating the amygdala even more which sends out more cortisol. Cortisol also decreases the activity of the hippocampus, an internal brain structure that helps not only detect threats but forms new memories. Thus, memory formation is disrupted.
All in all, when an emotional threat is experienced stress emotions escalate and get the brain and body ready for action and increasing a focus on negative information. In this way, fear and anger become dominant reactions in stressful situations. As these brain and body reactions increase, the activity of the prefrontal cortex decreases. The prefrontal cortex, located just behind the forehead, is responsible for making plans, setting goals, and shaping emotions. Thus, an activation of the amygdala during times of stress leads to fear and anger that decreases our ability to reason, regulate our emotions or work the problem through, all of which are functions of the prefrontal cortex which is inhibited.
Over time, the ongoing activation of the brain and body can lead to depression, anxiety and a host of physical ailments including gastrointestinal disorders, decreased immune function, cardiovascular illness, and hormonal (decreased libido) and metabolic problems (type II diabetes).
This stress response evolved over time to help our ancestors survive in relatively dangerous environments. Although our environments have hanged considerably, our stress response has not. In order to mediate the stress response, we must actively utilize emotional regulation techniques including relaxation, meditation, cognitive-behavioral techniques and others to increase our ability to realistically interpret or to learn to reinterpret challenging events.
Submitted by Holly Houston, Ph.D. Licensed Clinical Psychologist
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