Abstract
How a stimulus is perceived is contingent on the physical properties of the stimulus and the neural state of the individual perceiving it. Specifically, research has demonstrated that voluntary actions modulate neural responses in sensory regions and the corresponding perception of their sensory consequences relative to otherwise physically identical stimuli from an external source. Although the functional significance of such modulations is unknown, one possibility is that they sharpen the neural representation of expected sensory outcomes. We used fMRI to investigate the neural representation of visual shapes during active shape tracing and passive viewing of similar dynamic shape traces. We hypothesize that motor engagement facilitates the distinction between the neural representation of different shapes. We operationalize this by examining the decoding accuracy levels of fMRI activity in visual regions evoked by two different visual shapes. In the scanner, participants completed three experimental conditions: Active tracing of two distinct shapes using an MR-compatible drawing board, viewing dynamic shape traces of those stimuli collected outside the scanner, and viewing static images of the two shapes. Additionally, participants completed localizers to identify visual regions sensitive to shapes and visual motion. Preliminary data (n=9) demonstrated that the active trace condition resulted in higher shape classification levels in visual regions relative to observing shape traces. This was manifested by more voxels demonstrating high classification rates, greater mean classification rates, and higher maximum classification rates across voxels in the active condition. This pattern of results is compatible with the notion that the neural representation of visual shapes is sharpened by motor engagement.