Posterior parietal cortex control of reach-to-grasp movements in humans.

The aim of the present study was to ascertain the neural correlates for the integration of visual information with the control of the reach-to-grasp action in the healthy human brain. Nine adult subjects (18-38 years; four females and five males) were scanned using functional magnetic resonance imaging while reaching-to-grasp a three-dimensional target. Results demonstrated differential activation of the parietal cortices according to the number of potential targets to be taken into account before movement initiation and the variability of target location. Comparing conditions where a target object that can appear at an unpredictable location with conditions where the target object appears at a predictable location revealed activations in the left superior parietal lobule, the left parieto-occipital sulcus and the right intraparietal sulcus. Results are discussed in terms of visual selective attention and action planning.