Forming tool use representations: a neurophysiological investigation into tool exposure.

Prior work has identified a common left parietofrontal network for storage of tool-related information for various tasks. How these representations become established within this network on the basis of different modes of exposure is unclear. Here, healthy subjects engaged in physical practice (direct exposure) with familiar and unfamiliar tools. A separate group of subjects engaged in video-based observation (indirect exposure) of the same tools to understand how these learning strategies create representations. To assess neural mechanisms engaged for pantomime after different modes of exposure, a pantomime task was performed for both tools while recording neural activation with high-density EEG. Motor planning-related neural activation was evaluated using beta band (13-22 Hz) event-related desynchronization. Hemispheric dominance was assessed, and activation maps were generated to understand topography of activations. Comparison of conditions (effects of tool familiarity and tool exposure) was performed with standardized low-resolution brain electromagnetic tomography. Novel tool pantomime following direct exposure resulted in greater activations of bilateral parietofrontal regions. Activations following indirect training varied by tool familiarity; pantomime of the familiar tool showed greater activations in left parietofrontal areas, whereas the novel tool showed greater activations at right temporoparieto-occipital areas. These findings have relevance to the mechanisms for understanding motor-related behaviors involved in new tools that we have little or no experience with and can extend into advancing theories of tool use motor learning.