Repeated practice of a Go/NoGo visuomotor task induces neuroplastic change in the human posterior parietal cortex: an MEG study.

The posterior parietal cortex (PPC) is strongly related to task performance by evaluating sensory cues and visually guided movements. Sensorimotor processing is improved by task repetition as indicated by reduced response time. We investigated practice-induced changes in PPC visuomotor processing during a Go/NoGo task in humans using 306-channel magnetoencephalography. Eleven healthy adult males were instructed to extend the right index finger when presented with the Go stimulus (a red circle), but not to react to the NoGo stimulus (a green circle or a red square). Magnetic fields over the visual, posterior parietal, and sensorimotor cortices were measured before and after 3 days of task practice. The first peak of the visual-evoked field (VEF) occurred at approximately 80 ms after presentation of either the Go or NoGo stimulus, while a PPC response, with latency to a peak of 175.8 ± 26.7 ms, occurred only after the Go stimulus. No significant change in the first peak of VEF was measured after 3 days of task practice, but there was a significant reduction in the latency to peak PPC activity (160.1 ± 27.6 ms) and in the time from peak PPC activity to electromyogram onset. In all participants, practice resulted in a significant reduction in reaction time. These results demonstrate that practicing a sensorimotor task induces neuroplastic changes in PPC that accelerate sensorimotor processing and reduce motor response times.