Hand-dependent and hand-independent cerebral asymmetries in the praxis representation network during planning of functional grasps
26.51, Saturday, 17-May, 2:45 pm - 6:45 pm, Pavilion
Gregory Kroliczak1, Lukasz Przybylski1, Szymon Bidula1, Mikolaj Pawlak1, 2; 1Action and Cognition Laboratory, Institute of Psychology, Adam Mickiewicz University, Poznan, Poland, 2Department of Neurology and Cerebrovascular Disorders, Poznan University of Medical Sciences, Poland
When planning function-appropriate grasping actions with their right hands, right-handers show left-lateralized cerebral activity in caudal temporal, inferior parietal, and middle frontal cortices, especially when demanding visuomotor transformations are required. We investigated whether or not similar asymmetries are evident when such actions are planned with the use of the left hand. Methods. Brain activity was measured in an event-related design (cf. Kroliczak & Frey, 2009) while 12 right-handed participants performed the following tasks with their dominant, and non-dominant hands: (1) planning functionally-appropriate grasps directed at tools, (2) planning control grasps directed at non-tool objects matched for complexity, (followed by (3) pantomimed execution of the functional and (4) pantomimed execution of control grasps). These actions were cued by high-resolution images of graspable tools and non-tool objects presented at three different angles in their foreshortened views, emulating 3D viewing. Only planning-related effects are considered here. A paired-samples T-test was used to compare activity from contrasts of planning functional vs. control grasps for the right, and for the left hand (independent of the required hand rotation). Results. Except for significantly greater suppression in the left, and significant increases of activity in the right sensorimotor cortices for the non-dominant hand, the networks mediating planning of function-appropriate grasping actions for either hand did not differ. Interestingly, the increases of activity in the caudal middle temporal, fusiform, and middle frontal gyri were exclusively left lateralized, independent of the hand used. Conclusions: These results provide evidence that regions involved in the sensorimotor control of hand actions participate in the planning of function-appropriate grasps only for the non-dominant hand. Moreover, although areas involved in motor cognitive functions such as grasp planning may show some hand-specific modulations, the hand-independent representations of these skills are located primarily in the left hemisphere, and contribute to early affordance-based processing of tools.