Abstract
The parietal lobe hosts different areas involved in linking sensory information to signals useful to control arm movements. One area of the inferior parietal lobule, area AIP, is the parietal grasping area for antonomasia. Recently, also one area of the superior parietal lobule, area V6A, has been found to be involved in encoding grasping (Fattori et al., 2010 J. Neurosci; Fattori et al., 2012 J. Neurosci). In this work, we tested grasping responses of single V6A neurons with the same tasks used to study the lateral grasping area AIP (Murata et al., 2000 J. Neurophysiol). Delayed grasping actions were performed by two monkeys towards five objects of different shapes (so to require different grip types) either in full vision or in complete darkness. In a second task, the same objects were observed without performing grasping. We recorded 200 V6A neurons, and quantified the neural activity during grasping preparation, execution, and object holding and during object observation. The overwhelming majority of neurons (94%) resulted to be task-related. Most of task-related cells were influenced by visual background. Half of the neurons were excited by the visual input, half were inhibited. Similarly to AIP, V6A contains Visual cells, activated only during grasping in light; Motor neurons, equally activated during grasping in dark and in light; Visuomotor cells, differently activated while grasping in dark and in light. A subpopulation of grasp-related cells discharged also while the monkey observed the objects outside the grasping context. Most of the Visual, Motor, and Visuomotor neurons, highly or moderately selective for the object during grasping, lost their selectivity during object observation. A frame emerges where the two grasping parietal areas share some functional properties useful to update and control prehension, as the hand approaches an object, but with a different weight of sensory signals.
Meeting abstract presented at VSS 2017