Wednesday, July 14, 2010

Why stuttering at low stress/load levels

A reader asks the following question:
Can anyone explain how a late onset completely destroys a previous stable system even when going back to low stress-demand situations? I can almost fathom that when the stress/load is large enough the system jams and breaks down AT THAT LEVEL but why does the system break permanently in the previous lower stress/load levels? Is there a physical rewiring that sets due to the low plasticity? Is it like a breaking dam that once broken is never fixed? Any thoughts?
That is a good question leading to a good debate. I wish more people would ask such questions. Here is my answer:
  1. a person who has a late onset might already have an on-the-edge stable system. Such systems are very common in all kinds of situations. Think of a transport system, where you have not jam and just five minutes later there is a jam.
  2. a late onset is not destroying the stable system, but a relatively small change in neurotransmitter levels or neurological incident can push a stable system over the edge. And this is not destruction but modulation of the capacity of the system.
  3. the over-the-edge is not dramatic but just noticeably increases frequency and length of a jam in the brain under high stress/demand.
  4. this low capacity system leads to learned behaviours (secondaries or associations of letters with jams) and cognitive beliefs (I have trouble of those situation, I am scared that I will stutter.)
  5. those learned behaviours and cognitive beliefs lead to stuttering behaviours without a neurological jamming.
  6. I would not talk about a breaking dam but more like a dripping (a bit like Chinese torture: let water drip on a prisoner for a few hours) that will lead to maladaptive reactions.


Ora said...

One possible explanation:

Once the stuttering begins, it's not really possible to go back to the low-stress situations as they were before. The experience of stuttering, with all the accompanying anxiety, changes our expectations, so that situations that were previously low-stress now play out with the memory of the experience of stuttering, and these situations are now inevitably "infected" with the fear of stuttering that wasn't there previously.

So a situation that was previously a low-stress situation is no longer a low-stress situation, because of the additional stress and anxiety that the stuttering has brought.

This is probably also one of the reasons why stutterers have bad periods. During periods of less stuttering, we don't expect to stutter as much, and that lessens the anxiety. But during periods of more stuttering, situations that were previously easy become harder. Expectations affect performance.

ig88sir said...

So is there a structural change in the Rolandic Operculum (white matter connections) or a change in neurotransmitter levels? For example, is it the bridge or the goods that pass through it that is changed? This "occurrence" must happen due to some environmental factor (turning on the genes).

Do you think this occurrence has a higher probability of happening in a younger child as the brain is more malleable then? If so why does it happen to teenagers and even adults? Isn't the brain placticity very low by then? I know of a person who started stuttering at 18 when entering college.