Neural control of saccades and grasping movements towards objects in space

The posterior parietal cortex is important for sensory-motor integration. While the anterior part of the intraparietal sulcus (AIP) is involved in object grasping and stereo processing (Gallese et al., 1994; Durand et al., 2007), a more posterior part (lateral intraparietal area, LIP) has typically been implicated in attention and saccades (Colby et al., 1996; Corbetta and Shulman, 2002). Furthermore, both areas show selectivity for simple 2D shapes (Sereno and Maunsell, 1998; Janssen et al., 2008; Romero et al., 2014). The interplay between area LIP and neighboring area AIP may constitute the neural basis of eye-hand coordination in object manipulation, as human observers always fixate certain landmark positions in a visual scene in which objects have to be grasped (Johansson et al., 2001). Our working hypothesis is that increased activity in anterior LIP neurons and/or posterior AIP neurons– which possess rudimentary shape sensitivity – may identify potential landmark positions on objects in the visual field. Neurons in posterior LIP subserve the planning of eye movements and the shift of attention towards the selected object. Next, AIP neurons will signal the 3D structure of the object-to-be-grasped to plan the appropriate grasp. We will test this hypothesis by simultaneously recording single-unit activity, multi-unit activity and local field potentials throughout the entire intraparietal sulcus during a delayed visually guided grasping task.