Functional imaging studies of attention shifts ( Corbetta et al., 1998), delayed saccades ( Sereno et al., 2001), and reaching and grasping ( Culham et al., 2003) all report activity in PPC during these tasks. Lesions to parietal cortex can result in neglect or apraxia, deficits of attending to space, and planning motor movements ( Heilman and Gonzalez Rothi, 1993 Mesulam, 1999). The function of posterior parietal cortex (PPC) has been characterized in terms of space-based attention and motor intention. PPC regions thus have prominent response properties associated with memory, which may arise through interactions with medial temporal cortex. These studies demonstrate that retrieval success effects in lateral and medial PPC regions are not affected by manipulations predicted by classical theories of PPC function but can be modulated by memory-related manipulations. In a third study, IPLC and PCC activity was modulated at retrieval based on levels of processing at study, suggesting sensitivity to memory demands. IPLC, PCC, and pC/Rsp continued to show retrieval success effects with similar magnitudes for all response contingencies, including a condition in which no responses were made to old items. In two other conditions, subjects responded only to old or only to new items. In one condition, subjects responded to both old and new items. Study 2 explored a recognition task with varied response contingencies to investigate whether these retrieval success effects are dependent on motor intentions. A region lateral to the intraparietal sulcus and two regions in the medial PPC showed strong retrieval success effects for both picture and sound stimuli. Study 1 investigated old-new recognition using picture and sound stimuli to test whether PPC memory effects were dependent on visuospatial attention. Here, we explored the relationship between memory processes and classical notions of PPC function. Imaging studies of long-term memory have demonstrated PPC activation during successful memory retrieval.
Current theories of posterior parietal cortex (PPC) function emphasize space-based attention and motor intention.
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