Investigating Internal Models During Motor Imagery Practice

Abstract

In overt movement, internal models predict the sensory consequences and generate motor commands for desired movements. Sensory feedback updates internal models resulting in adaptation and improved performance. It’s unclear if internal models update during motor imagery, the mental rehearsal of movement. To investigate this, 66 participants were exposed to a leftwards prism shift while performing actual pointing movements (physical practice; PP), imagined pointing movements (motor imagery; MI), or no pointing movements (control). We hypothesized MI would show aftereffects like PP, indicating updating of internal models. After prism exposure, PP showed significant aftereffects (4.73°± 1.56°), but MI and control did not (0.34°± 0.96° and 0.34°± 1.04°, respectively). PP differed significantly from MI and control. This suggests that motor imagery does not update internal models and thus is not a simulation of overt movement. Understanding the mechanisms that underlie learning through motor imagery will lead to more effective applications of motor imagery.