Differences between actual and imagined usage of chopsticks: an fMRI study.

We examined neural basis underlying tool-use behavior to discuss whether or not the usage of a well-learned tool has a specific route. Regional cerebral blood flow was measured in healthy Japanese subjects using functional magnetic resonance imaging (fMRI) during object pick-up using chopsticks, object pick-up using the hand, pantomiming the use of chopsticks, imagining the use of chopsticks, and imagining the use of the hand. First, the left inferior parietal lobule (IPL) was found to selectively contribute to tasks requiring explicit retrieval of tool-related hand movements that were pantomiming task and imagery task. This finding provides supporting evidence for the ideomotor apraxia (IMA) model proposed by Buxbaum (2001). However, departing from Buxbaum's (2001) proposal, the actual use of a well-learned tool displays distinct processing routes to those for pantomime and imagining. A comparison of these tasks revealed that activation in the lateral part of the right cerebellum increased during execution of tool-use, and this activity was considered to reflect the internal model for tools proposed by Imamizu et al. (2000, 2003).