Neural oscillatory activity and connectivity in children who stutter during a non-speech motor task

Abstract

Neural motor control rests on the dynamic interaction of cortical and subcortical regions, which is reflected in the modulation of oscillatory activity and connectivity in multiple frequency bands. Motor control is thought to be compromised in developmental stuttering, particularly involving circuits in the left hemisphere that support speech, movement initiation and timing control. However, to date evidence comes from adult studies, with limited understanding about motor processes in childhood, closer to the onset of stuttering. In this study, we investigated the neural control of movement initiation in children who stutter and children who do not stutter by evaluating transient changes of EEG oscillatory activity and connectivity during a simple button press motor task. We found reduced modulation of left hemisphere oscillatory power, phase locking to button press and phase connectivity in children who stutter compared to children who do not stutter, consistent with previous findings of dysfunction within the left sensorimotor circuits. Interhemispheric connectivity was also weaker at lower frequencies (delta, theta) and stronger in the beta band in children who stutter than in children who do not stutter. Taken together, these findings indicate weaker engagement of the contralateral left motor network in children who stutter even during low-demand non-speech tasks, and suggest that the right hemisphere might be recruited to support sensorimotor processing in childhood stuttering. Differences in oscillatory dynamics occurred despite comparable task performance between groups, indicating that altered balance of cortical activity might be a core aspect of stuttering, observable during normal motor behavior.