Early-stage chunking of finger tapping sequences by persons who stutter and fluent speakers
Department of Communication Sciences and Disorders , St Cloud State University , St Cloud, MN , USA.Clinical Linguistics & Phonetics (Impact Factor: 0.58). 01/2013; 27(1):72-84. DOI: 10.3109/02699206.2012.746397
This research note explored the hypothesis that chunking differences underlie the slow finger-tap sequencing performance reported in the literature for persons who stutter (PWS) relative to fluent speakers (PNS). Early-stage chunking was defined as an immediate and spontaneous tendency to organize a long sequence into pauses, for motor planning, and chunks of fluent motor performance. A previously published study in which 12 PWS and 12 matched PNS practised a 10-item finger tapping sequence 30 times was examined. Both groups significantly decreased the duration of between-chunk intervals (BCIs) and within-chunk intervals (WCIs) over practice. PNS had significantly shorter WCIs relative to PWS, but minimal differences between groups were found for the number of, or duration of, BCI. Results imply that sequencing differences found between PNS and PWS may be due to differences in automatizing movements within chunks or retrieving chunks from memory rather than chunking per se.
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ABSTRACT: ABSTRACT The authors investigated the integrity of implicit learning systems in 14 persons with Parkinson's disease (PPD), 14 persons who stutter (PWS), and 14 control participants. In a 120-min session participants completed a verbal serial reaction time task, naming aloud 4 syllables in response to 4 visual stimuli. Unbeknownst to participants, the syllables formed a repeating 8-item sequence. PWS and PPD demonstrated slower reaction times for early but not late learning trials relative to controls reflecting delays but not deficiencies in general learning. PPD also demonstrated less accuracy in general learning relative to controls. All groups demonstrated similar limited explicit sequence knowledge. Both PWS and PPD demonstrated significantly less implicit sequence learning relative to controls, suggesting that stuttering may be associated with compromised functional integrity of the cortico-striato-thalamo-cortical loop.Journal of Motor Behavior 07/2013; 47(2). DOI:10.1080/00222895.2013.812058 · 1.42 Impact Factor
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ABSTRACT: Purpose: Stuttering individuals show speech and nonspeech sensorimotor deficiencies. To perform accurate movements, the sensorimotor system needs to generate appropriate control signals and correctly predict their sensory consequences. Using a reaching task, we examined the integrity of these control and prediction components separately for movements unrelated to the speech motor system. Method: Nine stuttering and 9 nonstuttering adults made fast reaching movements to visual targets while sliding an object under the index finger. To quantify control, we determined initial direction error and end point error. To quantify prediction, we calculated the correlation between vertical and horizontal forces applied to the object-an index of how well vertical force (preventing slip) anticipated direction-dependent variations in horizontal force (moving the object). Results: Directional and end point error were significantly larger for the stuttering group. Both groups performed similarly in scaling vertical force with horizontal force. Conclusions: The stuttering group's reduced reaching accuracy suggests limitations in generating control signals for voluntary movements, even for nonorofacial effectors. Typical scaling of vertical force with horizontal force suggests an intact ability to predict the consequences of planned control signals. Stuttering may be associated with generalized deficiencies in planning control signals rather than predicting the consequences of those signals.Journal of Speech Language and Hearing Research 09/2014; 57(6). DOI:10.1044/2014_JSLHR-S-13-0333 · 2.07 Impact Factor
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ABSTRACT: The ability to express thoughts through fluent speech production is a most human faculty, one that is often taken for granted. Stuttering, which disrupts the smooth flow of speech, affects approximately 5% of preschool-age children and 1% of the general population, and can lead to significant communication difficulties and negative psychosocial consequences throughout one’s lifetime. Despite the fact that symptom onset typically occurs during early childhood, few studies have yet examined the possible neural bases of developmental stuttering during childhood. Here we present a diffusion tensor imaging study that examined white matter measures reflecting neuroanatomical connectivity (fractional anisotropy; FA) in 77 children (40 controls [20F], 37 who stutter [16F]) between 3-10 years of age. We asked whether previously reported anomalous white matter (WM) measures in adults and older children who stutter that were found primarily in major left hemisphere tracts (e.g., superior longitudinal fasciculus) are also present in younger children who stutter. All children exhibited normal speech, language, and cognitive development as assessed through a battery of assessments. The two groups were matched in chronological age and socioeconomic status. Voxel-wise whole brain comparisons using tract based spatial statistics (TBSS) and region of interest analyses of FA were conducted to examine white matter changes associated with stuttering status, age, sex, and stuttering severity. Children who stutter exhibited significantly reduced FA relative to controls in WM tracts that interconnect auditory and motor structures, corpus callosum, and in tracts interconnecting cortical and subcortical areas. In contrast to controls, FA changes with age were either stagnant or showed dissociated development among major brain areas in children who stutter. These results provide first glimpses into the neuroanatomical bases of early childhood stuttering, and possible white matter developmental changes that may lead to recovery versus chronic stuttering. The white matter changes point to possible structural connectivity deficits in children who stutter, in inter-related neural circuits that enable skilled movement control through efficient sensorimotor integration and timing of movements.Brain 01/2015; 138(3). DOI:10.1093/brain/awu400 · 9.20 Impact Factor
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