The effect of delayed auditory feedback on activity in the temporal lobe while speaking: a positron emission tomography study.

PURPOSE

Delayed auditory feedback is a technique that can improve fluency in stutterers, while disrupting fluency in many nonstuttering individuals. The aim of this study was to determine the neural basis for the detection of and compensation for such a delay, and the effects of increases in the delay duration.

METHOD

Positron emission tomography was used to image regional cerebral blood flow changes, an index of neural activity, and to assess the influence of increasing amounts of delay.

RESULTS

Delayed auditory feedback led to increased activation in the bilateral superior temporal lobes, extending into posterior-medial auditory areas. Similar peaks in the temporal lobe were sensitive to increases in the amount of delay. A single peak in the temporal parietal junction responded to the amount of delay but not to the presence of a delay (relative to no delay).

CONCLUSIONS

This study permitted distinctions to be made between the neural response to hearing one's voice at a delay and the neural activity that correlates with this delay. Notably, all the peaks showed some influence of the amount of delay. This result confirms a role for the posterior, sensorimotor "how" system in the production of speech under conditions of delayed auditory feedback.