CogniFit's Science blog: Cognition And The Effects Of Stuttering On The Brain

Cognition And The Effects Of Stuttering On The Brain

The King’s Speech is a movie that revealed a great deal, won countless awards, and was greatly perceived by the people. One area that certainly stuck out was stuttering and how volume can play tricks on the minds of those who stutter.

Without the ability to hear their own voice, people with a stuttering problem no longer stumble over words. And new findings reveal cognition and the effects of this speech impediment on the brain better than ever.

The trick of masking one’s voice with another volume works because of the way the brain is organized for the stutterer. A neural setup affects the brain and how it works with other actions besides speech, a new study says.

Typically, speech requires the brain to control movement of the mouth and vocal chords using the sound of your own voice as a guide. It is the integration of movement and hearing that will happen in the brain’s left hemisphere known as the premotor cortex.

For those who stutter, the process actually occurs in the right hemisphere most likely because of a slight defect on the left side. This cognition is similar in singing as it requires a similar integration of aural input and motor control. The difference is this process occurs in the right hemisphere explaining why those who stutter can sing just as strong, if not better than others.

The new study published in an issue of Cortex shows unusual neural organization underlies a stutter along with motor tasks that are completely unrelated to speech. For the study, a group of 30 adults were used; half stuttered and half did not. Each subject tapped their finger in time to a metronome.

As the scientists interfered with the function of their left hemisphere using a noninvasive technique that temporarily dampens brain activity, those who did not stutter were unable to tap in time. However, those who did stutter were unaffected.

Cognition was gained when researchers then interfered with the right hemisphere, which coincidentally reversed the results. The stuttering group became impaired while those who did not stutter were just fine.

As a result, the study shows that the left-hemisphere defect underlying a stutter will ultimately negatively affect the sensory integration rather than specifically with speech-related problems like it has always been thought. It is now apparent that the right side will jump in and compensate, but the brain part that has not evolved cannot handle those tasks and begins to emerge.