Motor sequence learning and developmental dyslexia.

Beyond the reading-related deficits typical of developmental dyslexia (DD), recent evidence suggests that individuals afflicted with this condition also show difficulties in motor sequence learning. To date, however, little is known with respect to the characteristics of the learning impairments, nor to the neural correlates associated with this type of procedural deficit in DD patients. Here, we first summarize the results of the few behavioral and brain imaging studies that have investigated the effects of DD on motor sequence learning. To help guide research in this field, we then discuss relevant psychophysical and neuroimaging work conducted in healthy volunteers in relation to three different conceptual perspectives: when, how, and what. More specifically, we examine the cognitive boundaries that affect performance across the different stages of learning (i.e., "when"), the different cognitive processes (i.e., "how") under which learning occurs, and the mental representations (i.e., "what") that are elicited when acquiring this type of skilled behavior. It is hoped that this conceptual framework will be useful to researchers interested in further studying the nature of the motor learning impairment reported in DD.