IC‐P3‐182: Neural correlates of long‐term declarative memories reveal age‐dependent differences

Autobiographical episodic memory is considered to be the most complex subsystem of human long-term declarative memory combining information of multiple sources including the general knowledge of one's past and episodic event memories in a specific temporal, spatial and emotionally meaningful context. The purpose of the present study was to investigate whether age influences the neural activity associated with content (episodic versus semantic) and remoteness (recent versus remote) of memories. We performed fMRI in 12 healthy elderly (mean age 60.5 years, SD 5.7) and 12 young subjects (mean age 28.0 years, SD 3.3) and analysed neural activity related to memory content and remoteness (remote events from the time when they were 5–15 years old and recent events from the last five years). The stimuli used during the fMRI study were based on autobiographical episodic memory items that included recollection and re-experiencing context-rich events of the participant's own life (episodic memories) and were contrasted with the retrieval of semantic memory items including public events of the same time period. When comparing both age groups many commonalities in the activated network subserving declarative long-term memory and specifically autobiographic memory were revealed, however, two key differences emerged. In the elderly, retrieval of declarative long-term memories irrespective of remoteness led to a significant activation of parieto-occipital areas bilaterally when compared to the young. During re-experience of recent autobiographical and semantic event memories both groups significantly activated left posterior cingulate areas. Young subjects but not the elderly additionally activated hippocampus and orbitofrontal cortex. Our data suggest that there are age-dependent differences in the neural networks underlying declarative long-term memory and retrieval of recent autobiographical episodic and semantic event memories.