Older adults show reduced high frequency oscillatory patterns in both recent and remote spatial memory retrieval compared to younger adults

The concept of healthy ageing and its impact on spatial navigation and memory ability is well-established in the literature. However, the neural basis of these age-related changes is not well understood. In particular, there is limited research that examines the impact of healthy ageing on the neural mechanisms underlying spatial memory retrieval for memories encoded recently (24-hours ago) compared to those encoded remotely (1-month ago). This study attempted to explore the neural basis of recent and remote spatial memory retrieval during navigation in older adults (n = 21) compared to younger adults (n = 31) using EEG and a virtual maze task. Our results suggest that although both recent and remote memories were poorer in older compared to younger adults, older adults’ remote memories were relatively well preserved. In parallel, we showed reduced high-frequency oscillations in older adults for both recent and remote conditions compared to younger adults. Specifically, older adults showed decreased activation at 15 – 30 Hz (beta) as well as a failure to increase activation at 30 – 40 Hz (gamma) frequencies when compared to younger adults. While remote memory evoked increases in delta and theta (2 - 7 Hz) frequencies compared to recent memories in both age groups, older adults showed significantly less increase. We suggest that these differences could relate to the storage of the memories and the regions required for retrieval. The results are discussed in terms of age-related compensation for spatial navigation skills in healthy ageing.