D04 Interrelation between intracranial EEG activity, local field potentials and action potentials during memory encoding and retrieval in the human mediotemporal lobe

What are neural predictors of successful formation of human long-term memory (LTM)? During recent years several EEG characteristics have been identified which are closely related to LTM encoding and retrieval. In this project, we focus on predictors based on neural signals recorded from the mediotemporal lobe in presurgical epilepsy patients. There is converging evidence for several system- level predictors of LTM in terms of intracranial EEG measures. However, it is still unclear which phenomena correspond to these effects on the cellular level in terms of local field potentials and action potentials. For instance, successful LTM encoding has been shown to be associated with increased rhinal-hippocampal phase synchronization in the low gamma range. According to current models of LTM, this increased phase synchronization, mediated by spike-field coupling, may correspond to an enhanced synchronization of action potentials, which may facilitate neural communcation and plasticity. However, direct evidence supporting this hypothesis is still lacking. In this project, we aim to investigate such interrelations by analysing combined macro/microelectrode recordings from presurgical epilepsy patients performing different LTM tasks. These data may bridge the gap between knowledge about system and cellular level processes supporting successful LTM and may provide critical missing links in current models of LTM.