Visual pathways for object-oriented action and object recognition: functional anatomy with PET

The purpose of this study was to identify the functional anatomy of themechanisms involved in visually guided prehension and in object recognitionin humans. The cerebral blood flow of seven subjects was investigated bypositron emission tomography. Three conditions were performed using thesame set of stimuli. In the 'grasping' condition, subjects were instructedto accurately grasp the objects. In the 'matching' condition, subjects wererequested to compare the shape of the presented object with that of theprevious one. In the 'pointing' condition (control), subjects pointedtowards the objects. The comparison between grasping and pointing showed aregional cerebral blood flow (rCBF) increase in the anterior part of theinferior parietal cortex and part of the posterior parietal cortex. Thecomparison between grasping and matching showed an rCBF increase in thecerebellum, the left frontal cortex around the central sulcus, the mesialfrontal cortex and the left inferior parietal cortex. Finally, thecomparison between matching and pointing showed an rCBF increase in theright temporal cortex and the right posterior parietal cortex. Thusobject-oriented action and object recognition activate a common posteriorparietal area, suggesting that some kind of within-object spatial analysiswas processed by this area whatever the goal of the task.