The Hippocampus and Memory Integration: Building Knowledge to Navigate Future Decisions

Everyday behaviors require a high degree of flexibility, in which prior knowledge is applied to inform behavior in new situations. Such flexibility is thought to be supported in part by memory integration, a process whereby related memories become interconnected in the brain through recruitment of overlapping neuronal populations. Mechanistically, integration is thought to occur through specialized hippocampal encoding processes that integrate related events during learning. By recalling past events during new experiences, connections can be created between newly formed and existing memories. The resulting integrated memory traces would extend beyond direct experience in anticipation of future judgments that require consideration of multiple learned events. Recent advances in cognitive and behavioral neuroscience have provided empirical evidence for the existence of such a mechanism, with hippocampal encoding mechanisms—in coordination with medial prefrontal cortex—supporting memory integration. Emerging research suggests that abstracted representations in medial prefrontal cortex guide reactivation of related memories during new encoding events, thus promoting hippocampal integration of related experiences. Moreover, recent work indicates that integrated memories can impact a host of behaviors, from promoting spatial navigation and imagination to resulting in memory distortion and deletion.