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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.

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This study investigated whether a warm-up exercise consisting of 100 submaximal concentric contractions would attenuate delayed-onset muscle soreness (DOMS) and decreases in muscle strength associated with eccentric exercise-induced muscle damage.Ten male students performed two bouts of the elbow flexor exercise consisting of 12 maximal eccentric contractions with a warm-up exercise for one arm (WU) and without warm-up for the other arm (control: CON) in a randomised, counterbalanced order separated by 4 weeks.Muscle temperature of the biceps brachii prior to the exercise was compared between the arms, and muscle activity of the biceps brachii during the exercise was assessed by surface integral electromyogram (iEMG). Changes in visual analog scale for muscle soreness and maximal voluntary isometric contraction strength (MVC) of the elbow flexors were assessed before, immediately after, and every 24 hours for 5 days following exercise, and compared between the WU and CON conditions by a two-way repeated measures ANOVA. The pre-exercise biceps brachii muscle temperature was significantly (p < 0.01) higher for the WU (35.8  0.2ºC) than CON condition (34.4  0.2 ºC), but no significant differences in iEMG and torque produced during exercise were evident between conditions. Changes in muscle soreness and MVC were not significantly different between conditions, although these variables showed significant (p<0.05) changes over time. It was concluded that the warm-up exercise was not effective in mitigating DOMS and loss of muscle strength following maximal eccentric exercise.