Neural pattern stability within events is similar in young and older adults.

Understanding how the brain segments continuous experiences into discrete events is essential for uncovering the mechanisms of episodic memory. Here, we investigated whether stable neural representations are maintained within unfolding events, how these representations differ between young and older adults, and whether they predict later memory. Young (N = 42) and older adults (N = 42) watched a 35-min clip from BBC's Sherlock while EEG was recorded. Using representational similarity analysis, we quantified neural pattern similarity within events and across event boundaries. Neural similarity was significantly higher within events than across events, even after controlling for perceptual changes in the stimulus, indicating stable neural representations during ongoing experience. This within-event neural stability was observed in both young and older adults, although evidence was stronger in young adults. Despite robust neural effects, neither within- nor across-event neural similarity significantly predicted subsequent free recall at the event or subject level. These findings suggest that neural stability reflects top-down maintenance of coherent event representations during perception, rather than directly determining later recall success. Importantly, both age groups showed greater within-event than across-event neural similarity, but follow-up analyses did not provide sufficient evidence to conclude equivalence between younger and older adults.