Stress and the brain

Here are some terms and definitions:

Amygdala

• small structure in the middle of the brain that unconsciously detects threats

• common misconception that the amygdala is the emotion center of the brain

Nucleus accumbens

• part of the brain that unconsciously picks a behavioral response based on which will produce the most dopamine

  • can also be thought of as determining which response will offer the greatest benefit

Dopamine

• brain chemical that measures how much benefit you will get as a result of an action

• common misconception that dopamine = pleasure

Cortisol

• hormone released in our bodies when we experience stress

• only beneficial because it helps us carry out actions

• problems arise when there’s nothing for us to do with the cortisol (i.e. there’s no action to take)

Stress

• the brain’s reaction to a perception of threat

  • in most present day situations, there is no real threat (to our survival)

Now that we have gotten some terms defined, let’s pull it all together.

Our amygdala constantly scans our environment for threats, which evolutionarily meant a danger to our basic survival. After the amygdala has detected the threat, the nucleus accumbens considers our possible behavioral responses (i.e. fight or flight) and determines which one will be most beneficial for us. Then after making that decision, our brain releases dopamine, in response to how much better our life is about to get as a result of that action, and our body releases cortisol to help us carry out our behavioral response (either fighting or fleeing).

*Reminder: this entire process happens unconsciously and very, very quickly.

This is helpful if the threat is that we are about to be attacked by a animal, but it becomes harmful when our threats are chronic, rather than acute, and neither fighting nor fleeing will resolve the danger.

Acute vs chronic stress

• Acute: short term, has a defined beginning, middle and end

  • examples- an animal attack, car accident, an argument with a family member or friend

• Chronic: constant and persistent, less definable event

  • examples- toxic workplace, living in a high crime neighborhood, abusive relationships

Our stress system is not made to be switched on all the time. High levels of cortisol causes the body to shut off “unnecessary” functions such as digestion, reproduction and immune systems (unnecessary in terms of survival- i.e. if we’re about to be killed by an animal, we don’t need to waste energy on digesting food). This is why when we experience chronic stress, it has a harmful effect on our physical health.

Information in this post was adapted from a continuing education class I recently attended called “Calming an Overactive Brain” presented by Brian E. King, Ph.D.