When humans perform movements and receive on-line visual feedback about their performance, the spatial qualities of the visual information alter performance. The spatial qualities of visual information can be altered via the manipulation of visual gain and changes in visual gain lead to changes in force error. The current study used functional magnetic resonance imaging during a steady-state precision grip force task to examine how cortical and subcortical brain activity can change with visual gain induced changes in force error. Small increases in visual gain <1° were associated with a substantial reduction in force error and a small increase in the spatial amplitude of visual feedback. These behavioral effects corresponded with an increase in activation bilaterally in V3 and V5 and in left primary motor cortex and left ventral premotor cortex. Large increases in visual gain >1° were associated with a small change in force error and a large change in the spatial amplitude of visual feedback. These behavioral effects corresponded with increased activity bilaterally in dorsal and ventral premotor areas and right inferior parietal lobule. Finally, activity in the left and right lobule VI of the cerebellum and left and right putamen did not change with increases in visual gain. Together, these findings demonstrate that the visuomotor system does not respond uniformly to changes in the gain of visual feedback. Instead, specific regions of the visuomotor system selectively change in activity related to large changes in force error and large changes in the spatial amplitude of visual feedback.
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