Final Report Summary - BRAINSHAPE (Objects in sight: the neural basis of visuomotor transformations for actions towards objects)
Object grasping is controlled by a network of cortical areas in the visual and the motor system. We have investigated the properties and functional connectivity of two key areas for the visual control of grasping actions, i.e. parietal area AIP and premotor area F5a, in the macaque monkey using an unprecedented combination of single-cell recordings, functional imaging (fMRI), electrical microstimulation, reversible inactivation and transcranial magnetic stimulation. The results of 13 studies that have been started or finalized since the start of the project reveal in the first place what aspects of objects and actions are being encoded by AIP and F5a neurons. Moreover, after having determined the properties of single neurons in AIP, we have elucidated the brain-wide network that is connected to area AIP using fMRI and microstimulation. We have then proceeded to reversibly inactivate one of the candidate areas that may provide input to AIP, i.e. parietal area CIP, during fMRI. Reversible inactivation of area CIP exerted profound effects on many areas in the parietal, the temporal and even the frontal cortex. Thus our results show how visual information may reach AIP and how this information is transformed into motor commands in the premotor cortex. Furthermore our findings are relevant for timely research questions such as the mirror neuron system in the monkey, the relationship between fMRI activity and single-cell activity in parietal cortex, the effects of electrical microstimulation on remote areas, and the reorganization of cortical networks after reversible inactivation.