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Lukasz Przybylski, Szymon Bidula, Mikolaj Pawlak, Gregory Kroliczak; Neural bases of planning and execution of functional grasps: an fMRI study. Journal of Vision 2014;14(10):305. doi: 10.1167/14.10.305.
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Neuropsychological and neuroimaging evidence implicates the praxis representation network (PRN) of the left cerebral hemisphere in mediating tool use skills. Whether or not this network is engaged in the planning of function appropriate grasping is unknown, though often assumed in neuroimaging works. Such assumptions are inconsistent with neuropsychological evidence for independent representations of grasp attributes and functional actions (Randerath et al. 2009). In this study we aimed to establish the basic neural underpinning of the planning and execution of visually guided functional grasps. Methods: Using standard neuroimaging parameters and an optimized event-related design (Kroliczak & Frey, 2009), we investigated this issue while 12 right-handed participants performed the following four tasks with their dominant hands: (1) planning of a functionally appropriate grasp of a tool (2) planning of a grasp of a non-tool control object matched for complexity (3) pantomimed execution of a just planned functional grasp, and (4) pantomimed execution of a just planned control grasp. The stimuli were high-resolution pictures of tools and non-tool graspable objects presented at three different angles (0, 135, and 225 degrees) in their foreshortened perspectives, thus convincingly emulating 3D viewing. Results: Tool vs. non-tool grasp planning revealed greater involvement of the bilateral parieto-frontal network, with the supramarginal, caudal middle temporal and fusiform gyri activity primarily/only on the left. Notably, planning of the most demanding grasps of tools (vs. simple grasps of control objects) engaged only left PRN. Conclusions: The observed parieto-frontal involvement cannot be accounted for either by object complexity differences or increased task demands (including end-state comfort effects) because we did not observe any significant differences between the two tasks during their execution. Thus, the greater engagement of the left-hemisphere praxis representation network for planning functional grasps reveals a genuine effect of an early affordance-based representation of tools.
Meeting abstract presented at VSS 2014
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