Hemispheric asymmetries in goal-directed hand movements are independent of hand preference

Asymmetries in the kinematics and neural substrates of voluntary right and left eye-hand coordinated movements have been accredited to differential hemispheric specialization. An alternative explanation for between-hand movement differences could result from hand preference related effects. To test both assumptions, an experiment was conducted with left- and right-handers performing goal-directed movements with either hand paced by a metronome. Spatiotemporal accuracy was comparable between hands, whereas hand peak velocity was reached earlier when moving with the left compared to the right hand. The underlying brain activation patterns showed that both left- and right-handers activated more areas involved in visuomotor attention and saccadic control when using their left compared to the right hand. Altogether, these results confirm a unique perceptuomotor processing specialization of the left brain/right hand system that is independent of hand preference.