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Patrizia Fattori, Elisa Santandrea, Rossella Breveglieri, Annalisa Bosco, Claudio Galletti; Encoding of reaching and grasping intentions from monkey medial parietal cortex. Journal of Vision 2018;18(10):427. doi: https://doi.org/10.1167/18.10.427.
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Single cell recording in the macaque demonstrated that the medial parietal cortex, besides encoding reaching, is involved also in encoding grasping (Fattori et al., 2010). MVPA applied to fMRI allowed brain imaging studies to confirm the involvement of dorsomedial visual stream in grasping in both monkeys (Nelissen et al., 2017) and humans (Gallivan et al., 2011). The medial parietal area involved in the control of grasping is area V6A, a visuomotor area also known to show motor-related discharges tuned by direction and depth of reaching (Fattori et al., 2005; Hadjidimitrakis et al., 2015), wrist orientation and grip formation (Breveglieri et al., 2016, 2017). Here we compared the activity of single V6A cells during an instructed-delay epoch before reaching and grasping, respectively, applying the same paradigm used in humans (Gallivan et al., 2011) to check whether, when the monkey was preparing the action, neural activity was predictive of the specific upcoming action. In analogy to previous fMRI research, we recorded neural activity when monkeys performed the task in the light, but also added a control condition where monkeys prepared and executed reaching and grasping in darkness. We analyzed the discharges of 91 V6A neurons and found that in about 60% of them, task-selective activity was present before action execution, differentiating between arm/hand movements aimed at reaching a specific location or at grasping an object. Most often stronger pre-movement activity was observed in grasping (68%) vs. reaching task (32%). Most importantly, striking consistency was observed between pre-movement and movement activities, suggesting that the former is a preparatory activity implementing suitable motor programs which support subsequent action execution. These data strengthen the emerging view that areas in the dorsomedial and dorsolateral visual stream act as cooperating routes for controlling the whole act of prehension.
Meeting abstract presented at VSS 2018
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