I'm now dealing with PCS, and I noticed that with good sleep and very low stress levels, my symptoms become much milder and I just feel OK.

But a little bit of stress, I noticed, will cause my symptoms to return and make my life harder for a few days (just a little bit of stress messes me up, sometimes for a few days). Without stress, I'm feeling 80%-90% of what I was before my mTBI (which was 2 months ago). Although that sounds good, if you put me in a slightly stressful situation for a minute or two, I'll feel 20%-30% of what I was before my mTBI, and I'll most likely stay with that feeling for a few days. And by stress, I don't mean something necessarily extreme - it could just be an argument with someone.

Is it known exactly why the concussed brain has intolerance for stress especially early in the recovery process? I mean, is there an explanation for what parts of the brain that are responsible for stress tolerance are functioniong more weakly after a concussion?

By the way, I'm learning neuroscience, pharmacology and biology at my free time, so I have some understanding in these areas.
As a part of my learning, I would like to understand the causes to the extreme sensitivity of the concussed brain to stressful situations.

Does anybody here know and can please give a detailed explanation about these stress tolerance mechanisms?

Thanks,
-ProAgonist

From what I understand, stress intolerance is due to a failure of part of the brain that filters out excessive stimuli so that the remaining stimuli is within the brain's ability to process. A large amount of brain processing energy is spent filtering out this stimuli. When this failure happens, the rest of the brain is overloaded with excessive stimuli. This is made even worse with PCS because much of the brain is already struggling to function.

There are likely other issues at play but this is likely the most problematic issue.

Thank you for your reply, Mark.

You said that from what you understand, there's a part of the brain that has difficulties filtering out excessive stimuli in PCS sufferers.

But what I don't understand is, how do all PCS sufferers get damage to this part? I mean, brain injuries are very different among different individuals. Some people may get an impact on the right side of the head, while others may get on the left side, back of the head or the upper part of the head.

So how does this part get damaged in all people who get TBIs, independently of the location of the trauma?

Also, why do most parts that get damaged in the brain make a good recovery, but this part doesn't recover very well? And is it not known yet exactly what is that part of the brain responsible for stress filtering or where it is located in the brain?

I would like to expand on this topic--

Inhibitory neurons use GABA primarily and are responsible for reducing over excitation. It is thought that ADD/ADHD is a disorder of poor inhibitory control.

http://www.medicaldaily.com/brains-n...healthy-289338

More on inhibition:
http://www.ncbi.nlm.nih.gov/pubmed/10924667

For learning about the nervous system this is a good site.
It was made for kids, but I think it is a good learning tool for everyone:
http://faculty.washington.edu/chudler/neurok.html

example of inhibitory neurons and pain:
https://faculty.washington.edu/chudler/pain.html

The Washington site is huge... but filled with useful information to help you understand your nervous system.

Thank you for your reply, mrsD.

The stress intolerance I was talking about is related to mTBI/TBI, not ADHD.

I do know that the GABA system dysfunctions in ADHD, although the major problem is the Dopamine metabolism - Dopamine is metabolised too fast and many of it cannot reach the receptors and activate them because of this problem.

As you have said, the GABA system doesn't work well enough in ADHD and this creates a problem with over-excitation, but it's not only GABA. Other inhibitory systems, such as the endocannabinoid system and the opioid system are also thought to be somewhat related to poor inhibition seen in ADHD patients.

The opioid and endocannabinoid systems are similar in their roles, and they are both integral parts of the reward system, together with GABA (dopamine/norepinephrine are related to "wanting" - they are important for reward prediction and motivation but are not part of the reward system). Unfortunatenly, both systems, motivation and reward show some dysfunctioning in ADHD patients (although the low dopamine is the biggest problem of ADHD).

It's important to notice that stress hormones/neurotransmitters such as Dopamine and Norepinephrine are important to self control, even though they are stimulating (too high or too low levels of dopamine will cause hyperactivity, for example, and normal levels are needed for self control).

But back to the main point - I have suffered stress tolerance problems since my mTBI and posted this here since I wanted to know what parts of the brain are exactly responsible for low stress tolerance after suffering a concussion. Also, I think that everyone suffers a cognitive decline in higher stress levels - it's just that it's more severe in PCS patients than in most people.

What I am reading in Science News articles lately is that there are hubs of neurons all thru the brain scattered, that move impluses all over. They are not "organs" like the hippocampus, etc, but little clusters of neurons.

example:
http://www.sciencedaily.com/releases...0929154714.htm

If you search "hubs of neurons in the brain" you'll find more.

Brain science is still very crude...you might not find definitive answers yet.

I still have the same struggles with stress 2 years after my concussion - I was just wondering - does it matter what part of the brain took the main whack?

I fell on my back so the first part of my brain to hit was the front - and the front seems to still have the most problems with pain as well as an increase of pain in stressful situations.

GB

The issues are far more complex that just what part of the head sustained the impact.