Abstract
Several theories of motor imagery are based on the premise that imagined movements are functionally equivalent to physical movements. A newer account, the Motor-Cognitive model, holds that imagined movements depend more on higher-order executive resources than physical movements do. According to this model, executive functions enable individuals to monitor and elaborate on the developing motor image while inhibiting the motor command from being physically executed. The dorsolateral prefrontal cortex (dlPFC) is considered a hub for various executive functions, such as inhibitory control and working memory. Thus, dlPFC is potentially an important region for motor imagery. The current study was designed to examine the functional role of dlPFC in motor imagery. Participants (n=24) physically performed and imagined performing a serial disc transfer task and tasks that assess executive functions (Go/No-Go, which measures response inhibition; N-back, which measures working memory). All tasks were performed before and after undergoing 20 minutes of anodal, cathodal, or sham transcranial direct current stimulation (tDCS) applied over the right dlPFC. Results from the disc transfer task showed that anodal tDCS significantly modulated imagined movement time (MT) more than physical MT, whereas cathodal and sham tdcs did not impact imagined MT compared to physical MT. None of the stimulation types affected performance on the Go/No-Go or the N-back tasks. Altogether, these findings suggest that the dlPFC may play a distinct role in motor imagery, but more research is required to clarify the reliance of motor imagery on executive functions such as response inhibition and working memory.
