A Positron Emission Tomography Study of Silent and Oral Single Word Reading in Stuttering and Nonstuttering Adults

TLDR

PET imaging has been widely applied to study language and related cognitive processes in both healthy and diseased populations. The study used 15O‑H₂O PET scanning to investigate the lateralization and functional distribution of cortical and subcortical activity during single‑word reading in stuttering versus non‑stuttering adults. Ten right‑handed male stuttering adults and matched non‑stuttering controls read single words silently or aloud while PET images were acquired, and statistical parametric mapping of task versus baseline images was used to assess within‑ and between‑group regional cerebral blood flow differences. Silent reading elicited greater left anterior cingulate activation in stuttering adults, suggesting heightened cognitive anticipation, while oral reading produced bilateral activation in both groups but with a left‑hemisphere dominance in non‑stuttering and right‑hemisphere dominance in stuttering participants, supporting atypical language lateralization in stuttering.

Abstract

Over the last decade positron emission tomography (PET) has been used extensively for the study of language and other cognitive and sensorimotor processes in healthy and diseased individuals. In the present study, [ 15 O]H 2 O PET scanning was used to investigate the lateralization and functional distribution of cortical and subcortical activity involved in single word reading in stuttering and non-stuttering individuals. Ten right-handed male stuttering adults and matched nonstuttering individuals were instructed to read individually presented single words either silently or out loud. Subtraction of functional brain images obtained during each of the two reading tasks, and during a non-linguistic baseline task, was used to calculate within-group and between-group differences in regional cerebral blood flow by means of statistical parametric mapping. Increased activation in the left anterior cingulate cortex (ACC) was observed during silent reading in the stuttering speakers but not in the nonstuttering group. Because of the hypothesized role of the ACC in selective attention and covert articulatory practice, it is suggested that the observed increased ACC activation in the stuttering individuals reflects the presence of cognitive anticipatory reactions related to stuttering. During the oral reading task, within-group comparisons showed bilateral cortical and subcortical activation in both the stuttering and the nonstuttering speakers. Between-group comparisons showed a proportionally greater left hemisphere activation in the nonstuttering speakers, and a proportionally greater right hemisphere activation in the stuttering individuals. The results of the present study provide qualified support for the hypothesis that stuttering adults show atypical lateralization of language processes.