Theta-alpha oscillations bind the hippocampus, prefrontal cortex, and striatum during recollection: Evidence from simultaneous EEG-fMRI

Recollection of contextual information represents the core of human recognition memory. It has been associated with theta (4-8 Hz) power in electrophysiological recordings and, independently, with BOLD effects in a network including the hippocampus and frontal cortex. Although the notion of the hippocampus coordinating neocortical activity by synchronization in the theta range is common among theoretical models of recollection, direct evidence supporting this hypothesis is scarce. To address this apparent gap in our understanding of memory processes, we combined EEG and fMRI during a remember/know recognition task. We can show that recollection-specific theta-alpha (4-13Hz) effects are correlated with increases in hippocampal connectivity with the prefrontal cortex and, importantly, the striatum, areas that have repeatedly been linked to retrieval success. Taken together, our results provide compelling evidence that low frequency oscillations in the theta and alpha range provide a mechanism to functionally bind the hippocampus, prefrontal cortex and striatum during successful recollection