Pre-stimulus oscillatory activity predicts successful episodic encoding for both young and older adults

Abstract

Healthy aging is associated with declines in episodic memory performance that are due in part to deficits in encoding. Emerging results from young adult studies suggest that the neural activity during the time-period preceding stimulus presentation is sensitive to episodic memory performance. It is unknown whether age-related declines in episodic memory are due solely to changes in the recruitment of processes elicited by stimuli during encoding or also in processes recruited in anticipation of these stimuli. Here, we recorded oscillatory EEG while young and old participants encoded visual and auditory words that were preceded by cues indicating the stimulus modality. Alpha oscillatory activity preceding and following stimulus onset was predictive of subsequent memory accuracy similarly across age. Frontal beta oscillations linked to semantic elaboration during encoding were reduced by age. Post-stimulus theta power was positively predictive of episodic memory accuracy for old but not young adults, potentially reflecting older adults' tendency to self-generate associations during encoding. Collectively, these results suggest that the preparatory mobilization of neural processes prior to encoding that benefits episodic memory performance is not affected by age.