Neural mechanisms underlying spatial realignment during adaptation to optical wedge prisms

Abstract

Visuomotor adaptation to a shift in visual input produced by prismatic lenses is an example of dynamicsensory-motor plasticity within the brain. Prism adaptation is readily induced in healthy individuals, andis thought to reflect the brain’s ability to compensate for drifts in spatial calibration between differentsensory systems. The neural correlate of this form of functional plasticity is largely unknown, althoughcurrent models predict the involvement of parieto-cerebellar circuits. Recent studies that have employedevent-related functional magnetic resonance imaging (fMRI) to identify brain regions associated withprism adaptation have discovered patterns of parietal and cerebellar modulation as participants corrected their visuomotor errors during the early part of adaptation. However, the role of these regions inthe later stage of adaptation, when ‘spatial realignment’ or true adaptation is predicted to occur, remainsunclear. Here, we used fMRI to quantify the distinctive patterns of parieto-cerebellar activity as visuomotor adaptation develops. We directly contrasted activation patterns during the initial error correction phase of visuomotor adaptation with that during the later spatial realignment phase, and found significant recruitment of the parieto-cerebellar network – with activations in the right inferior parietal lobe and the right posterior cerebellum. These findings provide the first evidence of both cerebellar and parietal involvement during the spatial realignment phase of prism adaptation.