The comparison of cortical activation patterns by active exercise,proprioceptive input,and touch stimulation in the human brain: A functional MRI study

Abstract

Active execution, proprioception, and touch discrimination are important for the execution of movement. In the current study, we attempted to compare the cortical activation patterns of active exercise, proprioceptive input, and touch stimulation in the normal human brain using functional MRI. Nine subjects were recruited for this study. Functional MRI was performed using 1.5-T with three tasks at a fixed rate. The active exercise and proprioceptive input were performed at the metacarpophalangeal joint using a specially equipped apparatus, and touch stimulation was applied on the dorsum of the hand using a rubber brush. We performed analysis using the region of interest (ROI) method, and calculated the laterality index (LI) to assess the relative activity in the ipsilateral versus the contralateral ROI. When active exercise or proprioceptive input were applied, the LI in the primary sensorimotor cortex (SM1) was significantly higher than that of touch stimulation. The supplementary motor cortex, cerebellum, and contralateral SM1 showed stronger activation during active exercise than during proprioceptive input or touch stimulation, and the opposite pattern was observed in the insula. We found that the LIs of active exercise and proprioceptive input were higher than the LI of touch stimulation. This suggest that touch stimulation may be a less lateralized function than active exercise and proprioceptive input.