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Rouhollah Abdollahi, Jan Jastorff, Guy Orban; Walking, climbing, grasping: Separate visual processing streams for different classes of actions. Journal of Vision 2011;11(11):966. doi: 10.1167/11.11.966.
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© ARVO (1962-2015); The Authors (2016-present)
The action observation pathway comprises areas in posterior superior temporal cortex and in parietal and premotor cortex. Recently, we could show that the parietal cortex is organized based on the action that is performed and the premotor cortex based on the effector employed. However, all stimuli used in the study showed fine manipulative actions (Jastorff et al., 2010). In this new study, we investigate the organization of the action observation pathway with respect to a broader class of actions. In a human fMRI experiment, we presented videos of three classes of actions: locomotion (walking), locomotion with the aid of hands (climbing) and fine manipulative hand actions (grasping). Static frames of the videos and random dot texture patterns animated with the optic flow present in the original videos served as control conditions. We obtained a significant interaction between grasping and walking and between grasping and climbing and thus enhanced activation for grasping compared to other action classes in phAIP and ventral premotor cortex. Stronger responses for climbing compared to walking and climbing compared to grasping were obtained in the SPL dorsal to the IPS and posterior to the post central sulcus, extending up to SPOC (Cavina-Pratesi et al., 2010). This activation also extended towards the medial side of the brain. The results for the interaction between walking and grasping were similar to the ones between climbing and grasping, however the activation sites were smaller. The interaction between walking and climbing was not significant. Our results indicate separate processing streams for fine manipulative actions on the one hand and locomotion on the other hand. Climbing actions, which include grasping with the hand as one component lead to similar activations as normal locomotion, yet the activation in the SPL is more extended.
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