The neurochemical basis of speech motor control

Speech production requires the rapid and intricate control of over 100 muscles in the face, vocal tract, and upper body. The movement of these muscles are closely controlled by chemical signals that tell the brain to stop and start movements.  Such signalling is caused by expression of the neurotransmitters, Gamma-aminobutyric acid (GABA) and glutamate.

It is possible that developmental stuttering is caused by differences in the concentrations of GABA and glutamate, or differences in other chemicals, such as Dopamine, that inhibit their function.

To better our understanding of the role of these chemicals in speech production and developmental stuttering we aim to investigate differences in their concentration between people who stutter and people who speak fluently and their relationship with speech fluency.

We use two non-invasive magnetic resonance imaging techniques to study these differences. Magnetic resonance spectroscopy (MRS) uses the small magnetic fields produced by the atomic structure of different molecules to identify present chemicals and measure their concentration. This technique is used to measure GABA and glutamate in several brain regions that are important for speech motor control; the supplementary motor area, the inferior frontal gyrus, and the basal ganglia.

The second method used is multi-parameter mapping (MPM). This technique shows us where in the brain iron collects. Iron is a byproduct of dopamine metabolism (the mechanism that allows brain cells to use up dopamine molecules). Therefore, iron deposition can be used as a proximal measure of dopamine, a chemical that otherwise cannot be measured non-invasively.

The study takes place over a single session, which lasts two hours. Before each session we will ask each participant about their speech. We are looking for people who stutter and people who speak fluently, aged 18+.

We pay travel and accommodation costs for you to come and visit us in Bangor! email Nia-Wyn Williams nww23pzp@bangor.ac.uk

This project is led by PhD researcher, Nia-Wyn Williams. 

Nia's work is funded by Bangor University