Item recognition and lure discrimination in younger and older adults are supported by alpha/beta desynchronization

Abstract

Our episodic memories vary in their specificity, ranging from a mere sense of familiarity to detailed recollection of the initial experience. Recent work suggests that alpha/beta desynchronization promotes information flow through the cortex, tracking the richness in detail of recovered memory representations. At the same time, as we age, memories become less vivid and detailed, which may be reflected in age-related reductions in alpha/beta desynchronization during retrieval. To understand age differences in the specificity of episodic memories, we investigated differences in alpha/beta desynchronization between younger (18–26 years, n = 31) and older (65–76 years, n = 27) adults during item recognition and lure discrimination.Alpha/beta desynchronization increased linearly with the demand for memory specificity, i.e., the requirement to retrieve details for an accurate response, across retrieval situations (correct rejections < item recognition < lure discrimination). Stronger alpha/beta desynchronization was related to memory success, as indicated by reliable activation differences between correct and incorrect memory responses. In line with the assumption of a loss of mnemonic detail in older age, older adults had more difficulties than younger adults to discriminate lures from targets. Importantly, they also showed a reduced modulation of alpha/beta desynchronization across retrieval demands. Together, these results extend previous findings by demonstrating that alpha/beta desynchronization dissociates between item recognition and the retrieval of highly detailed memories as required in lure discrimination, and that age-related impairments in episodic retrieval are accompanied by attenuated modulations in the alpha/beta band. Thus, we provide novel findings suggesting that alpha/beta desynchronization tracks mnemonic specificity and that changes in these oscillatory mechanisms may underlie age-related declines in episodic memory.