Persistent developmental stuttering as a cortical-subcortical dysfunction: Evidence from muscle activation

Abstract

Background: One contemporary view of stuttering posits that speech disfluencies arise from anomalous speech motor control. Purpose: To verify the rest muscle tension and speech reaction time of fluent and stuttering adults. Method: 22 adults, divided in two groups: G1 - 11 fluent individuals; G2 - 11 stutterers. Electromyography recordings (inferior orbicularis oris) were collected in two different situations: during rest and in a reaction time activity. Results: The groups were significantly different considering rest muscle tension (G2 higher recordings) and did not differ when considering speech reaction time and muscle activity during speech. There was a strong positive correlation between speech reaction time and speech muscle activity for G2 - the longer the speech reaction time, the higher the muscle activity during speech. Conclusion: In addition to perceptible episodes of speech disfluency, stutterers exhibit anomalies in speech motor output during fluent speech. Correlations with a possible cortical-subcortical disorder are discussed.