|The basal ganglia in the brain. Part of their job is to coordinate the vocal cords during speech. The basal ganglia's malfunctioning may result in a freezing of the vocal cords, leading to stuttering.|
|Detailed view of the basal ganglia|
Important summary of Dr Martin Schwartz's latest thinking on the cause of stuttering as follows, provided by Dr Schwartz himself per email. This is based on his article, "The Trigger for Stuttering", the full version of which can be read HERE.
1. Most of the struggle behavior which typically characterises stuttering is learned.
2. It is learned to release a locking of the vocal cords.
3. Traditional speech therapy attempts to work on the struggle behavior.
4. I attempt to work on the locking of the vocal cords.
5. Recent research suggests that the locking of the vocal cords represents a transient dysfunction of the basal ganglia under stress.
6. My recent article entitled "The Trigger For Stuttering" enumerates ten sources of stress which often occur simultaneously.
7. The vocal cords, in ongoing speech, have to open and close rapidly so they can meet the requirements for voiced and voiceless sounds.
8. They do this by making use of a principle in physiology called reciprocal inhibition.
9. Reciprocal inhibition means that when the muscles that close the vocal cords contract, the muscles which open them actively relax - and vice versa.
10. The basal ganglia control reciprocal inhibition of the vocal cords during speech.
11. When the basal ganglia cannot function properly there is a loss of reciprocal inhibition.
12. This manifests itself as a freezing of the vocal cords in an open or closed position, depending upon the phonetic requirements of the upcoming speech sound.
13. If there is a deficiency of thiamine or magnesium (for some) then the basal ganglia cannot function properly because there is a deficiency of a necessary neurotransmitter (perhaps GABA or acetylcholine).
14. For some people who stutter, if we give them thiamine or thiamine and magnesium, the basal ganglia can function normally and the locking of the vocal cords stops and thus the trigger is no more and without the trigger the stuttering is also no more.