Neural correlates of state estimation in visually guided movements: an event-related fMRI study.

State estimation of self-movement, based on both motor commands and sensory feedback, has been suggested as essential to human movement control to compensate for inherent feedback delays in sensorimotor loops. The present study investigated the neural basis for state estimation of human movement using event-related functional magnetic resonance imaging (fMRI). Participants traced visually presented curves with a computer mouse, and an artificial delay was introduced to visual feedback. Motor performance and brain activities during movements were measured. Experiment 1 investigated brain activations that were significantly correlated with visual feedback delay and motor error by parametrically manipulating visual feedback delay. Activation of the right posterior parietal cortex (PPC) was positively correlated with motor error, whereas activation of the right temporo-parietal junction (TPJ) was observed only in the group with a smaller increase in motor error with increased visual feedback delay. Experiment 2 involved parametric analysis of motor performance while controlling mouse movement speed during the task. Activity in the right TPJ showed a significant positive correlation with motor performance under the delayed visual feedback condition. In addition, activity of the PPC was greater when motor error was presented visually. These results suggest that the PPC plays a significant role in evaluating visuomotor prediction error, while the TPJ is involved in state estimation of self-movement during visually guided movements.