ABSTRACT
Humans exhibit considerable motor variability even across trivial reaching movements. This variability can be separated into specific kinematic components such as extent and direction, which are thought to be governed by distinct neural processes. Here, we report that individual subjects exhibit different magnitudes of kinematic variability, which are consistent (within individual) across movements to different targets and regardless of which arm (dominant or non-dominant) was used to perform the movements. Simultaneous fMRI recordings revealed that individual subjects also exhibited consistent fMRI variability across movements to different targets when performed with either arm. Cortical fMRI variability of individual subjects predicted their movement extent variability. This relationship was markedly stronger in fMRI responses of posterior-parietal cortex than primary motor cortex, suggesting that individuals with more variable movement planning, exhibit larger kinematic variability. We, therefore, propose that neural and kinematic variability are reliable and interrelated personal characteristics, which may underlie individual motor capabilities.
Footnotes
Conflict of Interest: The authors declare no competing financial interests.