Reduced memory precision in older age is associated with functional and structural differences in the angular gyrus

Abstract

Growing evidence indicates decreased fidelity of mnemonic representations to play a role in age-related episodic memory deficits, yet the brain mechanisms underlying such reductions remain unexplored. Using functional and structural neuroimaging and a continuous report task we examined how changes in two key nodes of the posterior-medial memory network, the hippocampus and the angular gyrus, might underpin loss of memory precision in older age. An age-related reduction in activity reflecting successful memory retrieval was observed in the hippocampus, whereas activity associated with graded variation in memory precision was decreased in the angular gyrus. Grey matter volume of the angular gyrus further predicted individual differences in memory precision in older age, beyond variation in successful memory retrieval. These findings highlight the importance of functional and structural integrity of the angular gyrus in constraining memory precision in older age, advancing current understanding of hippocampal and parietal contributions to age-related episodic memory decline.

Metacognitive Awareness and the Subjective Experience of Remembering in Aphantasia

“…While alternative strategy use has been favoured in previous studies as an explanation for unimpaired performance on tasks thought to require mental imagery by aphantasics (Jacobs et al, 2018;Keogh et al, 2021;Zeman et al, 2010), none until now have used probabilistic mixture modelling to investigate the visual fidelity of their memory representations, which should be particularly sensitive to the strength of visual imagery. Alternative probabilistic mixture models to the one used here can be applied to continuous report data (e.g., Bays, 2014), but two-component models describe this type of data well and have previously been used to separate long-term memory retrieval success and precision (Brady et al, 2013;Cooper et al, 2017Cooper et al, , 2019Harlow & Yonelinas, 2016;Korkki et al, 2020Korkki et al, , 2023Richter et al, 2016;Stevenson et al, 2018;Sutterer & Awh, 2016). Moreover, it should be noted that the current results did not change when a model-free measure of object memory performance, raw angular colour deviation, was analysed.…”

“…The CIELAB colour space is well suited for continuous manipulations of colour as a given distance between two colours in this space approximates their perceptual colour distance. This property of the CIELAB colour space has previously been leveraged to investigate the fidelity of both working memory retrieval (Bays et al, 2009;Zhang & Luck, 2008;Panichello et al, 2019) and long-term memory retrieval (Brady et al, 2013;Korkki et al, 2020Korkki et al, , 2023Richter et al, 2016). To minimise potential biases in colour memory, only objects without specific colour associations were selected for use as target stimuli in this study.…”

Demands on perceptual and mnemonic fidelity are a key determinant of age-related cognitive decline throughout the lifespan.

“…A high-fidelity representation closely matches the detail and complexity of the experience it is intended to capture. It has been suggested that the described age deficits arise in part from a decline in forming such high-fidelity, distinct representations and binding together stimulus features into qualitatively rich memory traces that allow for the veridical reinstatement of previously experienced events (Chen & Naveh-Benjamin, 2012; Fandakova et al, 2013, 2018; Koen & Rugg, 2019; Koen et al, 2020; Korkki et al, 2022; Naveh-Benjamin & Mayr, 2018; Park et al, 2012; Trelle et al, 2017).…”