However, so far, not much is known about the causes of persistent developmental stuttering, which is the most frequent speech disorder. Scientists have recently discovered that a hyperactive network in the right frontal part of the brain plays a crucial role in this deficit. It inhibits speech movement planning and execution, thereby interrupting the flow of speech.
What processes in the brain cause people to stutter? Previous studies showed imbalanced activity of the two brain hemispheres in people who stutter compared to fluent speakers: A region in the left frontal brain is hypoactive, whereas the corresponding region in the right hemisphere is hyperactive. However, the cause of this imbalance is unclear.
Does the less active left hemisphere reflect a dysfunction and causes the right side to compensate for this failure? Or is it the other way around and the hyperactive right hemisphere suppresses activity in the left hemisphere and is therefore the real cause of stuttering? Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig and at the University Medical Center Göttingen have now gained crucial insights: The hyperactivity in regions of the right hemisphere seems to be central for stuttering.
Parts of the right inferior frontal gyrus (IFG) are particularly active when we stop actions, such as hand or speech movements says Nicole Neef, neuroscientist at MPI CBS and first author of the new study.
If this region is overactive, it hinders other brain areas that are involved in the initiation and termination of movements. In people who stutter, the brain regions that are responsible for speech movements are particularly affected.
Two of these areas are the left inferior frontal gyrus (IFG), which processes the planning of speech movements, and the left motor cortex, which controls the actual speech movements. If these two processes are sporadically inhibited, the affected person is unable to speak fluently, explains Neef.
The scientists investigated these relations using Magnetic Resonance Imaging (MRI) in adults who have stuttered since childhood. In the study, the participants imagined themselves saying the names of the months.
Used image is representational.
What processes in the brain cause people to stutter? Previous studies showed imbalanced activity of the two brain hemispheres in people who stutter compared to fluent speakers: A region in the left frontal brain is hypoactive, whereas the corresponding region in the right hemisphere is hyperactive. However, the cause of this imbalance is unclear.
Does the less active left hemisphere reflect a dysfunction and causes the right side to compensate for this failure? Or is it the other way around and the hyperactive right hemisphere suppresses activity in the left hemisphere and is therefore the real cause of stuttering? Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig and at the University Medical Center Göttingen have now gained crucial insights: The hyperactivity in regions of the right hemisphere seems to be central for stuttering.
Parts of the right inferior frontal gyrus (IFG) are particularly active when we stop actions, such as hand or speech movements says Nicole Neef, neuroscientist at MPI CBS and first author of the new study.
If this region is overactive, it hinders other brain areas that are involved in the initiation and termination of movements. In people who stutter, the brain regions that are responsible for speech movements are particularly affected.
Two of these areas are the left inferior frontal gyrus (IFG), which processes the planning of speech movements, and the left motor cortex, which controls the actual speech movements. If these two processes are sporadically inhibited, the affected person is unable to speak fluently, explains Neef.
The scientists investigated these relations using Magnetic Resonance Imaging (MRI) in adults who have stuttered since childhood. In the study, the participants imagined themselves saying the names of the months.
Used image is representational.
