Abstract not found

Neglect is an acquired cognitive disorder characterised by inattention to one side of a stimulus or representational space. There are hemispheric asymmetries in its cause and in its effects, but no implemented computational model of neglect has incorporated these facts. We report a series of neural network simulations of the line bisection task and of a simplified "lexical" task; the two tasks embody some of the critical differences between general visuospatial neglect and neglect dyslexia. We test the hypothesis that simple, neuroanatomically realistic principles of connectivity in the nervous system can produce emergent behaviours that captures a wide range of quantitative and qualitative data observed in neglect patients presenting with general visuospatial neglect and/or neglect dyslexia. We model detailed data in neglect performance on visuospatial and lexical tasks, the differences resulting from RH damage and LH damage, and the dissociation between performance on lexical and non...

Development and early focal brain injury 2 Over the past ten years, we have made significant progress in addressing key questions concerning deficit and development after early stroke. We found evidence of subtle early impairment and subsequent development in each domain examined. However, the profiles of impairment and development differed across domains. Deficits of language acquisition are initially pervasive in that they are observed following injury to widely distributed brain areas. Spatial analytic deficits exhibit more specific patterns of brain-behavior association, similar to those observed among adults with injury to comparable brain regions. Had we been working in isolation, the separate investigators associated with this project may have reached very different conclusions about the nature of development following early injury. Instead, we were forced to look for ways to resolve the apparent disparity in our cross-domain findings. The model that best fits our data focuses on redefining the nature of early plasticity. Recent animal studies provide strong evidence that plasticity plays a central role in brain development. Brain organization is to a large extent

Children with early brain damage, unlike adult stroke victims, often go on to develop nearly normal language. However, the route and extent of their linguistic development are still unclear, as is the relationship between lesion site and patterns of delay and recovery. Here we address these questions by examining narratives from children with early brain damage. Thirty children (ages 3;7–10;10) with preor perinatal unilateral focal brain damage and their matched controls participated in a storytelling task. Analyses focused on linguistic proficiency and narrative competence. Overall, children with brain damage scored significantly lower than their age-matched controls on both linguistic (morphological and syntactic) indices and those targeting broader narrative qualities. Rather than indicating that children with brain damage fully catch up, these data suggest that deficits in linguistic abilities reassert themselves as children face new linguistic challenges. Interestingly, after age 5, site of lesion does not appear to be a significant factor and the delays we have witnessed do not map onto the lesion profiles observed in adults with analogous brain injuries. 1998 Academic Press More than 120 years ago, research on the effects of unilateral brain injury in adults led to the conclusion that the left hemisphere plays a specialized The research reported here has been supported by NINDS-NIH Grant P250-NS-22343 and NIDCD Grant R29 DC00539. We also thank Judi Fenson, Gretchen Chapman, and Shelley Flores for their help in data collection and transcription as well as the families who have graciously participated in this study. Address correspondence and reprint requests to Judy Snitzer Reilly, San Diego State University,