Abstract
Mounting behavioral evidence suggests that declines in both representational quality and controlled retrieval processes contribute to episodic memory decline with age. The present study sought neural evidence for age-related change in these factors by measuring neural differentiation during encoding of paired associates, and changes in regional BOLD activity and functional connectivity during retrieval conditions that placed low (intact pairs) and high (recombined pairs) demands on controlled retrieval processes. Pattern similarity analysis revealed age-related declines in the differentiation of stimulus representations at encoding, manifesting as both reduced pattern similarity between closely related events, and increased pattern similarity between distinct events. During retrieval, both groups exhibited increased recruitment of areas within the core recollection network, including the hippocampus and angular gyrus, when endorsing studied pairs, whereas younger adults exhibited increased recruitment of, and hippocampal connectivity with, lateral prefrontal regions during correct rejections of recombined pairs. These results provide evidence for age-related changes in representational quality and in the neural mechanisms supporting memory retrieval under conditions of high, but not low, control demand.
Footnotes
Funding: This research was supported by the BBSRC [grant number BB/L02263X/1], and was carried out within the University of Cambridge Behavioural and Clinical Neuroscience Institute, funded by a joint award from the Medical Research Council and the Wellcome Trust. A.N.T. was supported by a Cambridge Commonwealth Trust scholarship, R.N.H. by the UK Medical Research Council programme grant SUAG/010 RG91365, and J.S.S. by James S. McDonnell Foundation Scholar award #220020333.
Updated with revised abstract