Reach and Gaze Representations in Macaque Parietal and Premotor Grasp Areas

Abstract

Voluntary movements are frequently composed of several actions that are combined to achieve a specific behavior. For example, prehension involves reaching and grasping actions to transport the hand to a target to grasp or manipulate it. For controlling these actions, separate parietofrontal networks have been described for generating reaching and grasping actions. However, this separation has been challenged recently for the dorsomedial part of this network (area V6A). Here we report that the anterior intraparietal (AIP) and the rostral ventral premotor area (F5) in the macaque, which are both part of the dorsolateral parietofrontal network and causally linked to hand grasping movements, also represent spatial information during the execution of a reach-to-grasp task. In addition to grip type information, gaze and target positions were represented in AIP and F5 and could be readily decoded from single unit activity in these areas. Whereas the fraction of grip type tuned units increased toward movement execution, the number of cells with spatial representations stayed relatively constant throughout the task, although more prominently in AIP than in F5. Furthermore, the recorded target position signals were substantially encoded in retinotopic coordinates. In conclusion, the simultaneous presence of grasp-related and spatial information in AIP and F5 suggests at least a supportive role of these spatial signals for the planning of grasp actions. Whether these spatial signals in AIP and F5 also play a causal role for the planning of reach actions would need to be the subject of further investigations.

Partially Mixed Selectivity in Human Posterior Parietal Association Cortex

“…It may be that the large number of variables to which human AIP is selective may be a reflection of the versatility of using different tasks and that both human and NHP PPC areas are modulated by a very large number of variables. Indeed, several NHP studies in AIP have reported overlapping populations of cells tuned to grasp type and reach target consistent with mixed selectivity between effectors as presented here (Asher et al, 2007; Fattori et al, 2009; Lehmann and Scherberger, 2013, 2015). …”

Grasping Execution and Grasping Observation Activity of Single Neurons in the Macaque Anterior Intraparietal Area

“…In support of this idea is the observation that these neurons mostly responded to an ellipse entering the central visual field (close to the fixation point). Consistent with this hypothesis, Lehmann and Scherberger (2009) recently showed robust reach position signals in area AIP that were mainly encoded in retinotopic coordinates. Furthermore, TMS of the posterior parietal cortex in humans (Reichenbach, Bresciani, Peer, Bülthoff, & Thielscher, 2011;Chib, Krutky, Lynch, & Mussa-Ivaldi, 2009;Desmurget et al, 1999) interferes with the online control of visually guided reaches.…”

Functional Properties of Parietal Hand Manipulation–related Neurons and Mirror Neurons Responding to Vision of Own Hand Action

“…To verify whether the quality of tuning for these preferred grip types was maintained among the different tasks, we performed a receiver operator characteristic (ROC) analysis (Lehmann & Scherberger, 2013;Townsend, Subasi, & Scherberger, 2011). In the FH1, FH2, and FHE tasks, we used neuronal activity in a sliding window of 200-msec widths, which were shifted to 20-msec steps in the task sequence, and plotted the ROC curve for the two sets of grip types: the preferred versus the second or third grip.…”