We will use univariate and multivariate functional Magnetic Resonance Imaging (fMRI) techniques, surface and stereo EEG, and in depth single cell recording to investigate the role of human parietal lobe in the monocular or stereoscopic observation of actions performed by conspecifics either using their biological effectors or artificial implements (tools, spears, bicycle, microphone, etc). The fMRI techniques will provide evidence for segregated processing of different types of observed actions within the parietal cortex. The EEG techniques will provide the time course of the electric activity in the parietal regions in comparison to the events and dynamic changes in the video and the time course in other parts of the action observation network. The stereo EEG also provides a more precise localization than fMRI, serving as an important confirmation of the fMRI results. The single cell recordings are crucial to demonstrate the selectivity of the neuronal processes for actions observed, their postural or kinematic parameters or localization in the visual field. This selectivity is crucial to show the presence of mirror neurons for the different types of actions and the use of tools, to document the contribution of the parietal neurons to discrimination between actions, and to assess the benefits of stereoscopic viewing. This project should yield a comprehensive view of the role of parietal lobe in action planning and understanding, including using artificial implements, and pave the way for understanding how higher-order parietal cognitive processes are rooted in the simpler action planning and understanding capacities.