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Thursday’s Therapy
Our Traumatized Brain
~
An Over-Saturated Sponge
Stress and Memory
Chronic over-secretion of stress hormones adversely affects brain function, especially memory.
Too much cortisol can prevent the brain from laying down a new memory, or from accessing already existing memories.
{No Wonder We Thought We Were Losing Our Minds!}
The renowned brain researcher, Robert M. Sapolsky, has shown that sustained stress can damage the hippocampus, the part of the limbic brain which is central to learning and memory. The culprits are "glucocorticoids," a class of steroid hormones secreted from the adrenal glands during stress. They are more commonly known as corticosteroids or cortisol.
During a perceived threat, the adrenal glands immediately release adrenalin. If the threat is severe or still persists after a couple of minutes, the adrenals then release cortisol.
Once in the brain, cortisol remains much longer than adrenalin, where it continues to affect brain cells.
Cortisol Affects Memory Formation and Retrieval
Have you ever forgotten something during a stressful situation that you should have remembered? Cortisol also interferes with the function of neurotransmitters, the chemicals that brain cells use to communicate with each other.
Excessive cortisol can make it difficult to think or retrieve long-term memories. That's why people get befuddled and confused in a severe crisis. Their mind goes blank because "the lines are down."
They can't remember where the fire exit is, for example.
Why We Lose Our Memory
Stress hormones divert blood glucose to exercising muscles, therefore the amount of glucose--hence energy--that reaches the brain's hippocampus is diminished. This creates an energy crisis in the hippocampus which compromises its ability to create new memories.
That may be why some people can't remember a very traumatic event, and why short-term memory is usually the first casualty of age-related memory loss resulting from a lifetime of stress.
Cortisol and Temporary Memory Loss-Study
In an animal study, rats were stressed by an electrical shock, and then made to go through a maze that they were already familiar with. When the shock was given either four hours before or two minutes before navigating the maze, the rats had no problem. But, when they were stressed by a shock 30 minutes before, the rats were unable to remember their way through the maze.
This time-dependent effect on memory performance correlates with the levels of circulating cortisol, which are highest at 30 minutes. The same thing happened when non-stressed rats were injected with cortisol. In contrast, when cortisol production was chemically suppressed, then there were no stress-induced effects on memory retrieval.
According to James McGaugh, director of the Center for the Neurobiology of Learning and Memory at the University of California, Irvine. "This effect only lasts for a couple of hours, so that the impairing effect in this case is a temporary impairment of retrieval. The memory is not lost. It is just inaccessible or less accessible for a period of time."
Cortisol and the Degenerative Cascade
Normally, in response to stress, the brain's hypothalamus secretes a hormone that causes the pituitary gland to secrete another hormone that causes the adrenals to secrete cortisol.
When levels of cortisol rise to a certain level, several areas of the brain -- especially the hippocampus -- tell the hypothalamus to turn off the cortisol-producing mechanism. This is the proper feedback response.
The hippocampus, however, is the area most damaged by cortisol.
In his book, Brain Longevity, Dharma Singh Khalsa, M.D., describes how older people often have lost 20-25% of the cells in their hippocampus {and Dr. Bessel A. van der Kolk reminds us that for a time the traumatized victim – in our case, of traumatic grief – also has a shrunken hippocampus}, so it cannot provide proper feedback to the hypothalamus, so cortisol continues to be secreted.
{Boy, does this explain a lot of the traumatic episodes I have been through where I thought I was absolutely losing my mind – that when I most needed it, my mind seemed the least able to function for me so that
I Was Afraid To Trust My Own Mind!
This neurophysiological explanation of what is going on in our traumatized brains explains SO MUCH to me that was otherwise downright CRAZY-MAKING!}
This, in turn, causes more damage to the hippocampus, and even more cortisol production.
Thus, a Catch-22 "degenerative {And/Or Traumatic} cascade" begins, which can be very difficult to stop.
{You can say that again!}
Cortisol and Brain Degeneration-Study
Studies done by Dr. Robert M. Sapolsky, Professor of Neurology and Neurological Sciences at Stanford University, showed that lots of stress or exposure to cortisol accelerates the degeneration of the aging hippocampus.
And, because the hippocampus is part of the feedback mechanism that signals when to stop cortisol production, a damaged hippocampus causes cortisol levels to get out of control - further compromising memory and cognitive function.
The cycle of degeneration then continues. (Perhaps similar to the deterioration of the pancreas-insulin feedback system.
Building Memories-Neurogenesis-Study
The growth of new brain cells – a process called neurogenesis – is involved in new memory formation. Researchers at Princeton University report that, even in adulthood, thousands of hippocampal neurons were being generated per day.
In animal studies, the number of adult-generated neurons in the hippocampi of rats doubled after they performed specific behavioral tasks and training that involved associative learning. In contrast, tasks that did not require the hippocampus did not stimulate new cell growth.
"All of the species we examined showed evidence of substantial neurogenesis in adulthood," Princeton's Elizabeth Gould said. "These findings indicate that adult-generated hippocampal neurons are specifically affected by, and potentially involved in, associative memory formation."
{Parenthetical comments throughout this article are my own.}
All in all, our over-loaded, traumatized brains are like an over-saturated sponge~There's just not a lot more we can take in; we have quite enough already to process without adding any more! And the Cortisol hormone keeps putting us into fight-or-flight so that our verbal processes and cognitive functioning (i.e., planning what we must do to help ourselves) get pushed aside for us to get-in-touch-with at a later time, like it or not...
Thank you to The Franklin Institute, Research for Science Learning for this excellent and enlightening article! Next week, I hope to talk about some RELIEF we can find from the cortisol streaming through our grieving bodies! So please, stay tuned...
http://www.fi.edu/learn/brain/stress.html
