IMPAIRED auditory feedback has been suggested to cause stuttering, and subtle irregularities of audition have been reported in behavioural studies. To characterize processing at the auditory cortical level, we recorded neuromagnetic responses to monaural tones in nine stutterers and 10 fluent speakers while the subjects were reading silently, with mouth movements only, aloud, and in chorus with another person. The basic functional organization of the auditory cortices was found to be different in stutterers and controls. The altered inter-hemispheric balance in stutterers was affected by speech production, due to changes in the left auditory cortical representation, and more severely by self-paced than accompanied speech. This may lead to transient non-optimal interpretation of the auditory input and affect speech fluency.
1Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 2200, Espoo, FIN-02015 HUT, Finland
2Department of Neurology, Heinrich-Heine University, Düsseldorf, Germany
3Institute of General Psychology, Otto-von-Guericke University, Magdeburg, Germany
4,1Corresponding Author and Address
ACKNOWLEDGEMENTS: This work was supported by the Academy of Finland, the Human Science Frontier Program, and Deutsche Forschungsgemeinschaft SFB Z2. We thank Riitta Hari, Jussi Numminen, and Päivi Helenius for contributions during the first design phase of the experiment, and Olli V. Lounasmaa, Riitta Hari, Gabriel Curio, and Jyrki Mäkelä for comments on the manuscript.
Received 21 April 1998; accepted 26 April 1998