ABSTRACT
In this chapter, we describe two experiments that used functional imaging techniques to identify the neural correlates underlying the selection mechanisms employed to reach and grasp a specific object in the visual field. We asked participants to perform a reach-to-grasp action towards three-dimensional stimuli presented either in isolation or flanked by physically identical distractor objects. In Experiment 1, three stimuli were presented simultaneously, two of which abruptly retracted into the apparatus leaving the remaining stimulus as the target to be grasped. In Experiment 2, the target and distractors remained visible at all times. From comparing the condition in Experiment 1 where a target object appeared at an unpredictable location with a condition where the target object appeared at a predictable location, activations in the left parieto-occipital sulcus and the right intraparietal sulcus were found. In Experiment 2, where the distractors were visible at all times, only the right occipital cortex was found to become activated. These results demonstrate functional modules within the parietal cortex, thus providing a starting point from which to address theoretically motivated questions related to the selection-for-action process.
