Neural support of manual preference revealed by BOLD variations during right and left finger-tapping in a sample of 287 healthy adults balanced for handedness

AO_SCPLOWBSTRACTC_SCPLOWWe have identified the brain areas involved in Manual Preference (MP) in 143 left-handers (LH) and 144 right-handers (RH)). First, we selected the pairs of homotopic regions of interest (hROIs) of the AICHA atlas with significant contralateral activation and asymmetry during the right-hand and the left-hand Finger-Tapping (FT) both in RH and LH. Thirteen hROIs were selected, including the primary and secondary sensorimotor, and premotor cortices, thalamus, dorsal putamen and cerebellar lobule IV. Both contralateral activations and ipsilateral deactivations (reversed for the cerebellum) were seen in primary motor and somatosensory areas, with stronger asymmetries when the preferred hand was used. Comparing the prediction of MP with different combinations of BOLD variations in these 13 hROIs, the differences between movement of the preferred hand versus that of the non-preferred hand within the contralateral and/or ipsilateral cortices of 11 hROIS performed best at explaining handedness distribution, Handedness is thus supported by: 1-between-hand variations of ipsilateral deactivations of hand primary sensorimotor and secondary somatosensory cortices and 2-variations in regions showing the same profile in left and right-handers during the right or left FT. The present study demonstrates that right and left-handedness are not based on mirrored organization of hand control areas.