Electrophysiological Evidence of Working Memory Updating Deficits in Children with Learning Disabilities

Recent behavioral studies suggest that children with learning disabilities (LD) have difficulty in working memory (WM) updating. However, as behavioral performance represents the summed activity of multiple stages of processing, the temporal locus of the WM updating deficit remains unclear. Here, we used an event-related potential (ERP) paradigm to compare the temporal mechanisms of WM updating in 21 children with LD (aged between 10 and 12 years) and 21 age-matched controls while they performed the running memory task. Behavioral results showed that children with LD attained significantly lower accuracy when the task required updating. ERPs revealed that the occipital early P1 component and parietal late positive complex (LPC) amplitudes were lower in children with LD compared to controls when the task required children to remember a new stimulus. The LPC (1000-1500) amplitude correlated with the performance of academic and updating behavior. These results provide a novel electrophysiological evidence that children with LD have a specific impairment in early visual attention processing and lately WM updating.