Is overt stuttered speech a prerequisite for the neural activations associated with chronic developmental stuttering?

Four adult right-handed chronic stutterers and four age-matched controls co mpleted (H2O)-O-15 PET scans involving overt and imagined oral reading task s. During overt stuttered speech prominent activations occurred in SMA (med ial), BA 46 (right), anterior insula (bilateral), and cerebellum (bilateral ) plus deactivations in right A2 (BA 21/22). These activations and deactiva tions also occurred when the same stutterers imagined they were stuttering. Some parietal regions were significantly activated during imagined stutter ing, but not during overt stuttering. Most regional activations changed in the same direction when overt stuttering ceased (during chorus reading) and when subjects imagined that they were not stuttering (also during chorus r eading). Controls displayed fewer similarities between regional activations and deactivations during actual and imagined oral reading. Thus overt stut tering appears not to be a prerequisite for the prominent regional activati ons and deactivations associated with stuttering. (C) 2000 Academic Press.