[show abstract][hide abstract] ABSTRACT: Multiple studies have reported both functional and neuroanatomical differences between adults who stutter and their normally fluent peers. However, the reasons for these differences remain unclear although some developmental data suggest that structural brain differences may be present in school-age children who stutter. In the present study, the corpus callosum of children with persistent stuttering, children who recovered from stuttering and typically developing children between 9 and 12 years of age was compared to test if the presence of aberrant callosal morphology is implicated in this disorder. The total corpus callosum midsagittal area and area of each subsection consisting of the rostrum, anterior midbody, posterior midbody and splenium were measured using MIPAV (Medical Image Processing, Analysis, and Visualization). Voxel-based morphometry (VBM) was also used to compare white matter volume. No differences were detected in the corpus callosum area or white matter volume between children with persistent stuttering, children who recovered from stuttering and typically developing children. These results agree with dichotic listening studies that indicate children who stutter show the typical right ear advantage. Therefore, the neural reorganization across the midline shown in adults who stutter may be the result of long-term adaptations to persistent stuttering. LEARNING OUTCOMES: Educational objectives: After reading this article, the reader will be able to: (1) summarize research findings on corpus callosum development; and (2) discuss the characteristics of corpus callosum anatomy in stuttering.
Journal of Communication Disorders 04/2012; 45(4):279-89. · 1.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purpose of this study was to investigate whether brain activity related to the presence of stuttering can be identified with rapid functional MRI (fMRI) sequences that involved overt and covert speech processing tasks. The long-term goal is to develop sensitive fMRI approaches with developmentally appropriate tasks to identify deviant speech motor and auditory brain activity in children who stutter closer to the age at which recovery from stuttering is documented. Rapid sequences may be preferred for individuals or populations who do not tolerate long scanning sessions. In this report, we document the application of a picture naming and phoneme monitoring task in 3 min fMRI sequences with adults who stutter (AWS). If relevant brain differences are found in AWS with these approaches that conform to previous reports, then these approaches can be extended to younger populations. Pairwise contrasts of brain BOLD activity between AWS and normally fluent adults indicated the AWS showed higher BOLD activity in the right inferior frontal gyrus (IFG), right temporal lobe and sensorimotor cortices during picture naming and higher activity in the right IFG during phoneme monitoring. The right lateralized pattern of BOLD activity together with higher activity in sensorimotor cortices is consistent with previous reports, which indicates rapid fMRI sequences can be considered for investigating stuttering in younger participants. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to describe the: (1) use of functional MRI to study persistent developmental stuttering; (2) differences in brain activation between persons who stutter and normally fluent speakers; and (3) potential benefit of time efficient fMRI sequences combined with a range of speech processing tasks for investigating stuttering in younger populations.
Journal of fluency disorders 12/2011; 36(4):302-7. · 2.19 Impact Factor
[show abstract][hide abstract] ABSTRACT: Recent studies have implicated anatomical differences in speech-relevant brain regions of adults who stutter (AWS) compared to normally fluent adults (NFA). The present study focused on the region of the corpus callosum (CC) which is involved in interhemispheric processing between the left and right cerebral hemispheres. Two-dimensional segmentation of area and voxel-based morphometry were used to evaluate the corpus callosum. Results revealed that the rostrum and anterior midbody of the CC were larger in AWS than NFA. In addition, the overall callosa area was larger in AWS than NFA. The group comparison of white matter volume showed a cluster of increased white matter volume predominantly encompassing the rostrum across the midline portion in AWS. These results potentially reflect anatomical changes associated with differences in the hemispheric distribution of language processes that have been reported previously in AWS.
Journal of Communication Disorders 03/2011; 44(4):470-7. · 1.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: The present study examined whether abnormal cerebral control was evident in the lip movements of adult stutterers (AS) compared to non-stutterers (ANS), as demonstrated during speech and non-speech tasks. Electromyographic (EMG) activity during production of words with initial /f/ and /p/ phonemes, single-sentence production and lip pursing were measured. Differences between AS and ANS were evident in all tasks. For AS, the highest EMG amplitude was in the region of the left lower lip, which is indicative of greater right hemisphere participation. However, in ANS the right lower lip displayed the highest EMG amplitude, suggesting greater left hemisphere participation. Further, AS showed greater asynchronous lip activity than ANS for all tasks. These results support the hypotheses of reversed lateralization for speech and non-speech processing and reduced coordination of speech musculature in AS.
Folia Phoniatrica et Logopaedica 01/2010; 62(3):143-7. · 1.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Past research investigating stuttering has cited atypical cerebral lateralization in adults who stutter (AWS) during speech production. The purpose of this study was to measure cerebral activation in AWS as indicated by lip asymmetry. The study included five AWS (mean age = 26 years of age) and five adults who do not stutter (AWNS) (mean age = 25 years of age). The tasks included single-word productions, single-sentence readings and lip pursings. The peak electromyographic (EMG) amplitude was determined for the left upper, right upper, left lower and right lower lip quadrants around the mouth. Overall, EMG amplitudes were higher for the lower lip than the upper lip. Based on examination of peak EMG amplitude, significant differences were found between speaker groups. For both speech and non-speech tasks, the highest EMG amplitude for the AWS and AWNS groups were on the left lower and right lower sides of the mouth, respectively. The AWNS group showed strong correlations in EMG activity across the four lip sites (r>0.97), indicating an overall synchronous lip activity during speech and non-speech tasks. In contrast, the AWS group showed a strong correlation (r=0.97) only for the left upper and left lower lips while the other lip pairings were not strongly correlated (r<0.738) indicating otherwise reduced synchronous lip activity. While the small sample size suggests caution, clear differences in the pattern of lip EMG activity demonstrated in the present study provides evidence of differences between AWS and AWNS in the cerebral activation governing lip movement. The greater left lip activity observed in AWS was indicative of greater right hemisphere cerebral activation while increased right lip activity was indicative of greater left hemisphere participation in AWNS. The results of the present study provided support for the hypotheses of reversed lateralization for speech and non-speech processing and reduced coordination of speech musculature in AWS.