"The Cause of Stress and The Brain"
- Zooming In...

From the many symptoms of stress, we're now going to review the cause of stress and the brain's key participants in this positive feedback cycle...

The Amygdala, Hippocampus, and Hypothalamus

You might be more familiar with the amygdala and hippocampus as structures of the limbic, emotional brain. They respectively excite and inhibit the para-ventricular nucleus (PVN) of the hypothalamus.

Simplified,

the amygdala initiates stress responses to threatening stimuli by exciting the PVN, which then initiates a chain-reaction resulting in release of the stress hormone cortisol from the adrenal cortex.

Cortisol excites the amygdala and impairs the hippocampus's inhibition of the stress response, and in turn you're able to respond to the threat.

This is the fight or flight (anger or fear) response.

When the threat is gone the amygdala settles down and the hippocampus, through negative feedback, inhibits the PVN.

You're back to normal.

But if the stressful stimuli persist, the amygdala continues to excite the PVN-Cortisol release which continues to excite the amygdala. Now the hippocampus gets sidelined while the positive feedback cycle between the amygdala and PVN spins out of hippocampal control.

I emphasize here that a negative interpretation is a stressful stimulus because the brain also interacts with itself. This is very important to understand. Most of the time we initiate the fight or flight response when there's no real threat and no need for it.

If you change your mind, you change the feedback cycle - the meditation zone shows how to interrupt the cycle.

Continuing with the cause of stress and the brain...

Excessive cortisol over time is harmful to your heart and it also destroys the hippocampus's dendrites and their synapses (communication points). Over time, uninhibited stress kills brain cells in the hippocampus.

Considering the brain's massive interaction between its ten trillion synapses, and the hippocampus's vital role in short-term memory and learning - a vital part of the state of 'being' - a damaged hippocampus has severe emotional and behavioral consequences for its owner.

Next, we're zooming all in for a spine-tingling scene. This is depression and suicide.

Return from Stress and the Brain to Symptoms of Stress.





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