Planning of visually guided reach-to-grasp movements: inference from reaction time and contingent negative variation (CNV).

We performed electroencephalogram (EEG) recording in a precuing task to investigate the planning processes of reach-to-grasp movements in human. In this reaction time (RT) task, subjects had to reach, grasp, and pull an object as fast as possible after a visual GO signal. We manipulated two parameters: the hand shape for grasping (precision grip or side grip) and the force required to pull the object (high or low). Three seconds before the GO onset, a cue provided advance information about force, grip, both parameters, or no information at all. EEG data show that reach-to-grasp movements generate differences in the topographic distribution of the late Contingent Negative Variation (ICNV) amplitude between the 4 precuing conditions. Along with RT data, it confirms that two distinct functional networks are involved with different time courses in the planning of grip and force. Finally, we outline the composite nature of the lCNV that might reflect both high- and low-level planning processes.