Poster B127, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Motor cortex excitability during perception of dynamic handwritten and typed text
Chelsea Gordon1, Ramesh Balasubramaniam1; 1University of California, Merced
The motor system is active during the observation of actions performed by others and during the processing of action-related language. This suggests a role for the motor system in perception and language cognition (Rizzolatti et al., 1996; Pulvermüller et al., 2005). Recently it has been proposed that the motor system might also have a direct role in sensory prediction, even in the case of inanimate events (Schubotz, 2007). As contexts that recruit the motor system turn out to be broader than previously assumed, it could be that the role of the motor system in the perception-action-cognition loop is modulated by context. In this study, we look at corticospinal excitability using single-pulse transcranial magnetic stimulation (TMS) during the perception of written language to examine the extent of motor involvement. We found that while viewing videos of handwritten words and nonwords, there is consistent facilitation in motor-evoked potentials (MEPs) recorded from the first dorsal interosseous (FDI) muscle with each presentation of the stimulus, implicating a mechanism akin to the simulation of the inferred agent writing the stimuli. When subjects viewed videos of typed words and non-words, we observed a less pronounced facilitatory effect which is further reduced for each reoccurence of a stimulus. The data suggest that the role of the motor system in the processing of written language is a dynamic one that changes with situational context, allowing for simulation or prediction depending on its context.
Topic Area: PERCEPTION & ACTION: Motor control