Written by Matthew O’Malley
Article examined: Stuttering as a trait or state – an ALE meta-analysis of neuroimaging studies
Bibliographical Information: Belyk, M., Kraft, S. J., & Brown, S. (2014). Stuttering as a trait or state – an ALE meta-analysis of neuroimaging studies. European Journal of Neuroscience, 41(2), 275-284.
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. A link as well as bibliographical information is provided above.
Interpretation of article:
- There are differences in how the brains of people who stutter activate during periods of fluent speech in comparison to people who do not stutter during fluent speech. Generally, the differences are increased activation in the right hemisphere and decreased activation in the left hemisphere of people who stutter in comparison to fluent speakers (both during fluent speech). The most prominent difference was decreased activation in the left larynx motor cortex in people who stutter. The article gets more specific as to the exact brain regions which activate more or less.
- There are differences in brain activity in the person who stutters during fluent speech in comparison to the person who stutters during stuttered speech. There is more activation in the right larynx motor cortex during stuttered speech in people who stutter. Other patterns of brain activation differences observed were diverse (not easily summarized).
- Generally, people who stutter have more activation in the brain in motor areas and less activation in auditory areas in comparison to fluent speakers.
- One cannot draw conclusions based on this information as to whether these findings pertain to causation of stuttering or whether these brain differences are a result of accumulated stuttering behaviors/experiences.
- One must also be cautious with this information as there may be sub-types of stuttering. This study documents a general trend, however, some people who stutter may exhibit different brain functionality.
- Trait stuttering (a term used often in this article) compared brain activation imaging in people who stutter when speaking fluently to people who don’t stutter when speaking fluently.
- State stuttering (a term used often in this article) compared brain activation imaging in people who stutter when speaking fluently with people who stutter during stuttered speech.
Quotes from the article:
“the right IFG/frontal operculum overactivation is restricted to trait stuttering, (ii) underactivation of auditory cortex is common to both trait and state stuttering and (iii) while the cerebellar vermis is overactivated during state stuttering, it is underactivated in trait stuttering” (Belyk, Kraft, Brown, 2014)
“Trait stuttering was associated with an increased likelihood of activation almost exclusively in the right hemisphere and a decreased likelihood of activation almost exclusively in the left hemisphere. The analysis of state stuttering, on the other hand, revealed increases in both hemispheres and decreases exclusively in the right hemisphere.” (Belyk, Kraft, Brown, 2014)
“The combination of the two results suggests a potential lack of coordination in the cortical control of the laryngeal muscles.” (Belyk, Kraft, Brown, 2014)