Callosal transfer of finger localization information in phonologically dyslexic adults.

Dyslexia, particularly phonological dyslexia, has been hypothesized to be associated with deficits in interhemispheric interactions mediated by the corpus callosum. Twenty-one dyslexic subjects were compared to 21 controls on the Finger Localization Test in order to observe patterns of tactile-motor integration and interhemispheric collaboration. When compared to control subjects, dyslexics showed consistent deficits in finger localization, particularly when more complex trials had to be completed. When subjects were re-grouped according to phonological processing ability (regardless of diagnostic group membership), subjects with lower phonological processing scores were found to perform poorly on complex trials of finger localization, particularly on those trials which reflect callosal transfer of finger localization information from one hemisphere (hand) to the other. These results suggest that interhemispheric transfer of information is critical to efficient phonological processing.

Bimanual coordination in dyslexic adults.

Various types of dyslexia have been associated with tactile-motor coordination deficits and inefficient transfer of information between the two cerebral hemispheres. Twenty-one dyslexic adults were compared to 21 controls on the Bimanual Coordination Task, a test of tactile-motor coordination and interhemispheric collaboration. When compared to control subjects, dyslexics showed a consistent pattern of deficits in bimanual motor coordination, both with and without visual feedback. In particular, dyslexics had greater difficulty relative to normals when the left hand had to move faster than the right, and when the hands had to make opposite (mirror-image) movements, suggesting problems with interhemispheric modulation of visuomotor control. In addition, accuracy on this bimanual coordination task was significantly correlated with the Block Design subtest of the WAIS--R, but not with a rhyme fluency task, suggesting some contribution of right hemisphere controlled visuospatial skill to performance.

Assistive technology for postsecondary students with learning disabilities: From research to practice.

The article reports on a support services program for postsecondary students with learning disabilities that was found to be particularly conducive to the conversion of research findings into practical applications in such a way that it measurably enhanced students' immediate and long-term academic performance. The results of both clinical and controlled research on persons with learning disabilities were applied to: (1) the prescription of services and compensatory strategies, including assistive technology, in relation to the diagnosis of specific disabilities; and (2) the preparation of a written composition curriculum for persons with learning disabilities which emphasizes the use of assistive computer technology. The paper concludes with an identification of those elements in the setting that appeared to promote the collaboration of both researchers and practitioners. These included: (1) location of the research staff both geographically and administratively within the service delivery unit; and (2) specific opportunities to accomplish joint goals that required intense communication and interaction.

Handedness patterns in autism suggest subtypes.

The present study reports preliminary data from two unselected samples of carefully diagnosed autistic subjects (children and adults) and an assessment procedure that includes a large sample of items, appropriate for lower-functioning autistic subjects, with multiple presentations within and between sessions 1 week apart. The study seeks to determine (1) whether a raised incidence of non-right-handedness exists in these samples (2) if so, what constructs best represent this shift in the handedness distribution (i.e., phenotype and CNS substrate) and (3) whether these handedness phenotypes are associated with different levels of cognitive functioning. The results reveal a dramatic shift away from right-handedness in both autistic samples, due to a raised incidence of two phenotypes, manifest left-handedness and ambiguous handedness. The ambiguously handed, who were postulated to represent substantial bilateral CNS pathology due to early brain injury, were found to have much lower intellectual scores in one of the study samples.