Inter-limb and handedness differences in the adaptation to brief movement perturbations.

Abstract

Handedness or limb preference is a well-known aspect of upper-limb motor control lateralization. However, its impact on motor adaptation remains poorly understood. Here, using brief, force perturbations, we examined how inter-limb and handedness differences influence the online corrective response and adaptation when movement was randomly disrupted. We tested both limbs of human subjects (n = 50, 33 females) who exhibited different hand preferences. The correction to the perturbation (applied early, late, or mid-movement) was similar between limbs, but was significantly different between right- and left-handed individuals, with mixed-handed subjects falling in between. Similar to the corrections, the total force generated during the adaptive response differed significantly between right- and left-handed individuals, and in the majority of cases, mixed-handed subjects again fell between the two. In addition, the single-trial adaptation to the perturbation (i.e., the temporal force profile) was well-characterized by a linear combination of the scaled movement kinematics (i.e., the limb motion states-longitudinal position and velocity). Interestingly, handedness had less influence on how this movement information was integrated in the adaptive response; the dependence of the temporal pattern of force on movement velocity and position changed based on when the perturbation occurred and was significantly modified more for the left limb compared with the right. However, this spatiotemporal modulation was similar for right- and left-handed groups, but distinctly different for mixed-handed subjects. These results demonstrate 1) a systematic difference in motor corrections based on handedness and 2) inter-limb differences in how spatiotemporal properties influence the integration of motion-state information.NEW & NOTEWORTHY This study characterized performance differences influenced by handedness in upper limb motor control. Correction to movement perturbations changed based on handedness, with mixed-handed subjects showing behavior that was between right- and left-handed individuals. In addition, the motion state dependence of the adaptive response varied between limbs, with the left limb showing more sensitivity to the temporal properties of the perturbation. Our results provide novel insight into how handedness is reflected in the coding of limb motion.