Asymmetric transcallosal conduction delay leads to finer bimanual coordination

The role of transcallosal conduction delay (TCD) in hemispheric dominance and behavioral outcomes has long been theorized, but it has scarcely been investigated due to methodological shortcomings. Here, we report a new noninvasively measured index of TCD between homologous motor areas derived from TMS-evoked potentials. Notably, asymmetric TCD leads to finer bimanual coordination when signal is transmitted more quickly from the dominant primary motor cortex than in the opposite direction.