Bimanual control processes and the role of handedness

Bimanual movements are a fundamental motor skill. Whereas substantial research is available from right-handers, much less is known from left-handers. Accordingly, in the present electroencephalography (EEG) study we evaluated bimanual behavior in left- versus right-handers.

Thirteen left-handers and 13 right-handers took part in the experiment. Cortical dynamics were evaluated by means of EEG coherence in the beta frequency band (14-28 Hz), and behavioral performance was measured using motor error.

The EEG data revealed that right-handers showed a left-sided lateralization pattern whereas left-handers demonstrated a bilateral organization pattern during symmetrical actions. Asymmetry of the bimanual task demands modified the hemispheric profile for both groups and resulted in an additional involvement of the motor-nondominant hemisphere. Brain-behavioral correlations underlined that response planning strongly relied on the left hemisphere irrespective of handedness whereas the motor-dominant hemisphere drove response execution.

The findings suggest that skilled motor planning may develop preferentially in the left hemisphere.