Electrophysiological correlates of associative recognition memory for identity, spatial, and temporal relations

The formation of associative representations and their retrieval from episodic memory are vital cognitive functions. However, it is unclear to what extent retrieval of the basic component relations of episodic memory - identity, time, and space - requires different or shared brain mechanisms. In the current study, we employed EEG to track the time courses of electrophysiological correlates of retrieval processes of memory for identity relations, temporal order, and spatial configuration. Participants engaged in pair-associate learning of serially presented and spatially configured object picture pairs, followed by discrimination of identity, spatially, or temporally intact and rearranged pairs. Event-related brain potentials (ERPs) revealed distinct patterns of activity during successful retrieval of identity, spatial, and temporal relations that differed by the status of association, across the three retrieval time windows examined (300-500, 500-800, and 800-1000 ms). The identity relations condition was distinguished by a widespread greater negative-going deflection for rearranged relative to intact pairs in all three time windows. For the temporal relations condition, we observed a widespread more negative-going deflection for rearranged than intact pairs, significant in the second time window only. For the spatial relations condition, there was a widespread positive-going deflection greater for rearranged than for intact pairs, significant in the early and in middle time windows. These patterns of activity suggest that retrieval of associative memory traces for identity, spatial, and temporal relationships involve dynamically different processes, which may partially rely on different sets of basic associative mechanisms.