Mapping dexterity and handedness: recent insights and future challenges

Manual ability (dexterity) and hand preference (handedness) are key features of human motor control. Recent magnetic resonance imaging (MRI) studies casted new light on the neural underpinnings of dexterity. In right-handers, MRI identified structural brain features related to the right-left difference in dexterity or skill acquisition. Functional MRI disclosed a hierarchical and modular representation of discrete finger sequences in sensorimotor cortical areas and uncovered representational plasticity of the deprived sensorimotor cortex in congenital one-handers. Functional MRI studies also identified differences in sensorimotor activity and connectivity between right-handers and left-handers. However, these results are inherently ambiguous, because they may reflect a consequence of handedness rather than its underlying cause. We discuss future scientific strategies that might help to resolve this ambiguity.