The influence of the basal ganglia on stuttering
Presenters: Dr Katrin Neuman, University of Frankfurt; Prof. Henny-Annie Bijleveld, University of Brussels
By Tom Weidig, BSA research committee vice chair

For me, the most interesting topic was the theory of a basal ganglia dysfunction as a cause of persistent developmental stuttering (PDS). The basal ganglia is a set of brain structures that modify and control movement by sending timing cues to motor regions. The idea is that stuttering occurs due to improper initiation of speech sequences, and the basal ganglia does not deliver accurate timing cues to the speech motor regions.

Prof Bijleveld showed in her talk how this theory allows us to understand the interaction between psychological and physiological aspects of PDS. She introduced the main brain regions, the limbic system (the region that controls our emotions), the role of the basal ganglia and how a possible dysfunction in it could lead to emotion, stress or anxiety producing an increased dsyfunction of the basal ganglia, and more dysfluency. Thus, she effectively provided a single and concrete framework for unifying and understanding psychological and physiological aspects of PDS.

Dr. Neumann's talk fitted nicely with Prof Bijleveld's, as she described her research team's extensive brain imaging studies on the PDS brain and evidence for an involvement of the basal ganglia. They have looked at patients before and after a fluency shaping therapy.

Interestingly, they find that the basal ganglia activity is "modified by fluency shaping therapy through long-term therapy effects which are paralleled by an improvement of speech fluency and naturalness".

I find it very satisfying that brain research over the past few years has given us a closer look at what goes wrong inside the brain, and more effective theory building and testing than in the past is now possible. Let's see whether the basal ganglia theory stands the test of time.

Endnote: Also present at the conference was Dr Per Alm (Lund University, Sweden). He recently published an outstanding review article in Journal of Fluency Disorders on the basal ganglia theory.(TW)

From the Winter 2005 edition of Speaking Out

Internet link
Stuttering and the basal ganglia - article by Per Alm on the Stuttering Foundation of America website, including link to his doctoral thesis On the causal mechanisms of stuttering (2005)