Parietal and medial temporal lobe interactions in working memory goal-directed behavior.

Working memory is essential for the organization of goal-directed behavior, which involves multiple brain networks. The frontoparietal network has been proposed as a central node for the maintenance and manipulation of information. However, the exact contribution of the frontal and parietal lobes is still unclear as is that of the medial temporal lobe (MTL). Here, we investigated how the frontoparietal network and the MTL coordinate cognitive functions to control working memory in 12 participants, including five men, with medically intractable epilepsy. Participants performed a modified Sternberg working memory task during intracranial electroencephalography recording. The present working memory task was designed to test the different neural states of working memory subprocesses during memory maintenance and operation. First, we observed increased and sustained low-frequency (2-7 Hz) power in the frontal lobe and MTL, relative to baseline activity during the entire working memory task. Parietal alpha (8-13 Hz) power exhibited peak activity during memory operation. Finally, we found a positive correlation in the alpha band between the MTL and the parietal lobe during memory operation. These results indicate that as task demands become specific and goal-directed, the correlation between the MTL and the parietal lobe increases. This finding provides novel insight into the contribution of the MTL-parietal lobe network to voluntary control of working memory.