Prefrontal synthesis (PFS, also known as mental synthesis) is the conscious purposeful process of synthesizing novel mental images. PFS is neurologically different from the other types of imagination, such as simple memory recall and dreaming. Unlike dreaming, which is spontaneous and not controlled by the prefrontal cortex (PFC),[1] PFS is controlled by and completely dependent on the intact lateral prefrontal cortex.[2][3][4][5][6][7] Unlike simple memory recall that involves activation of a single neuronal ensemble (NE) encoded at some point in the past, PFS involves active combination of two or more object-encoding neuronal ensembles (objectNE). The mechanism of PFS is hypothesized to involve synchronization of several independent objectNEs.[8] When objectNEs fire out-of-sync, the objects are perceived one at a time. However, once those objectNEs are time-shifted by the lateral PFC to fire in-phase with each other, they are consciously experienced as one unified object or scene.
^Waltz, J. A.; Knowlton, B. J.; Holyoak, K. J.; Boone, K. B.; Mishkin, F. S.; de Menezes Santos, M.; Thomas, C. R.; Miller, B. L. (1 March 1999). "A System for Relational Reasoning in Human Prefrontal Cortex". Psychological Science. 10 (2): 119–125. doi:10.1111/1467-9280.00118. S2CID44019775.