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 non-stuttering 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 (PET) was used to image regional cerebral blood flow changes, an index of neural activity, and assessed 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, sensori-motor ‘how’ system in the production of speech under conditions of delayed auditory feedback