Research Glimpse, Treatment Implications: Stuttering, Affecting the Basal Ganglia

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Practical Stuttering Treatment Guide

Written by Matthew O’Malley

Note:  The content of this post is my interpretation of a research article.  I read and analyze research articles and aim to extract and simplify the most important findings.  In simplifying the information, much of the context of the research is lost.  To gain the full context of the research and to come to one’s own conclusions about the findings, one should always read the original article in its entirety which I will provide a link for, as well as bibliographical information.

Article Examined: Effect of an 8-week practice of externally triggered speech on basal ganglia activity of stuttering and fluent speakers (click title for link)

Bibliographical Information:
Toyomura, A., Tetsunoshin F., and Shinya K. “Effect of an 8-week Practice of Externally Triggered Speech on Basal Ganglia Activity of Stuttering and Fluent Speakers.” NeuroImage 109 (2015): 458-68.

My interpretation of what the study suggests:

Thoughts & Preface:  Many researchers are focused on the basal ganglia’s role in stuttering.  The basal ganglia is believed to play a role in initiating and controlling movement.  Studies have shown decreased activity in the basal ganglia of people who stutter in comparison to people who do not stutter.  The study in review looked at the brains of people who stutter and people who do not stutter using functional magnetic resonance imaging (fMRI), which is real-time brain imaging while individuals are performing tasks.  Below are the findings:

  • The study looked at the brains of people who stutter and people who do not stutter.  For both of these groups, they looked at the brains during metronomic speech (speaking to a rhythm provided by an external metronome) as well as self-paced speech (normal, everyday speech, where the speaker chooses and controls the pace how they see fit).
  • During self-paced speech, people who stutter showed significantly lower levels of activity in the basal ganglia in comparison to fluent counterparts during self-paced speech.
  • During metronomic speech, people who stutter showed approximately the same level of basal ganglia activity as their fluent counterparts.
  • The researchers had people who stutter speak to a metronome for about fifteen minutes per day for eight weeks and brought them back for more imaging.
  • At the end of the eight weeks, imaging of the brains of people who stutter was again collected during self-paced speech.  The lower levels of basal ganglia activity were no longer present.  The people who stutter showed significantly increased activity in the basal ganglia during self paced speech at the end of the 8 weeks of performing metronomic speech for fifteen minutes per day.
    • In other words, the eight weeks of metronomic speech for fifteen minutes per day erased the difference between level of basal ganglia activity in people who stutter during self-paced speech and people who do not stutter during self-paced speech.

Here are some stats to clarify the impact this had on people’s stuttering:

  • Participants averaged 51.7 days practiced out of 56  and averaged 878 minutes of total metronomic speech in that time span.
  • Mean stuttering score before 8-week intervention was 20.7 and after 8-week intervention was 13.8.
  • Speech naturalness before intervention was 5.2 and after intervention was 3.8 (Scale of 1-9, 1 being most natural).
  • People who stutter more severely improved more than people who stutter less severely based on this method.
  • Stuttering rates before intervention- 2.42 (self-paced) and .42 (metronome)
  • Stuttering rates after intervention –  1.62 (self-paced) and .28 (metronome)

Some limitations of the study:

  • I have no idea why they did this but it clouds the results a bit.  During all the fMRI’s digital auditory feedback (hearing one’s own voice) was placed in the ear of the person being examined under fMRI.
  • Few participants
  • This study focused on the basal ganglia.  The researchers believe “basal ganglia stuttering” may be a sub-type of stuttering or a factor in stuttering along with others.
  • Speech rate in this study was relatively slow (100 bpm).
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