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Fattori Patrizia, Annalisa Bosco, Rossella Breveglieri, Claudio Galletti; Visual responses of the dorsomedial area V6A to the presentation. Journal of Vision 2010;10(7):909. doi: 10.1167/10.7.909.
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© ARVO (1962-2015); The Authors (2016-present)
The medial posterior parietal area V6A has been recently shown to encode the different types of grips used to grasp objects of different shapes (Fattori et al., Journal Neurosci, in press). As V6A contains many neurons activated by visual stimulations (Galletti et al., 1996; 1999), and receives a direct visual input from the extrastriate visual area V6 (Galletti et al., 2001), the aim of the present study was to ascertain whether cells in V6A encode the visual features of the objects to be grasped. 153 neurons were recorded from 2 monkeys trained to perform reach-to-grasp movements to objects with different shapes: ball, handle, ring, plate, stick-in-groove. The monkeys fixated a LED, one object was illuminated for 500 ms, then, after a variable delay (0.5- 2s) the animal reached and grasped the same object in the dark. About 70% of V6A cells (109/153) showed visual responses to object presentation; 80% of these visual neurons (88/109) showed also reach-to-grasp-related discharges. About 30% of visual neurons displayed selectivity for an object or a set of objects (31/109), and half of these cells (17/31) showed reach-to-grasp responses modulated by the type of grip used to grasp them. At population level, the strenght of neural modulations to the visual features of objects to be grasped is similar to that for coding the grip postures suitable for grasping these objects. From these data it turns out that most of V6A neurons are visually driven by the objects presented in peripersonal space, with neurons discriminating the object type, and neurons able to code both object types and grip types. We conclude that area V6A is a visuomotor area of the dorsomedial visual stream involved in coding both the execution of reach-to-grasp actions and the visual features of objects to be grasped.
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