Novel Interaction between Prefrontal and Parietal Cortex during Memory Guided Saccades

Abstract Dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex (PPC) are linked to each other by direct reciprocal connections and by numerous pathways that traverse other areas. The nature of the functional coordination mediated by the interconnecting pathways is not well understood. To cast light on this issue, we simultaneously monitored neuronal activity in DLPFC (areas FEF and 8a) and PPC (areas LIP and 7a) while monkeys performed a memory guided saccade task. On measuring the spike-count correlation, a measure of the tendency for firing rates to covary across trials, we found that the DLPFC-PPC correlation became negative at the time of the saccade if and only if the neurons had matching spatial preferences and the target was at their mutually preferred location. The push-pull coordination underlying the negative spike-count correlation may help to ensure that saccadic commands emanating from DLPFC and PPC sum a constant value. Significance Anatomical pathways linking cortical areas that mediate executive control are thought to mediate coordination between them. We know very little, however, about the principles that govern this coordination. In the present study, we addressed this issue by recording simultaneously from neuronal populations in prefrontal and parietal cortex while monkeys performed memory guided saccades. We found a clear sign of coordination. Prefrontal and parietal neurons encoding a given saccade engage in a push-pull interaction during its execution. If parietal neurons are more active, prefrontal neurons are less active and vice versa. We suggest that this is a manifestation of a general principle whereby commands emanating from DLPFC and PPC are coordinated so as to sum a constant value. Footnotes NJH: Department of Neurobiology, Duke University, Box 3209, Durham, NC 27710.