Brain oscillatory processes related to sequence memory in healthy older adults

• Published in: Neurobiology of aging Vol. 139; pp. 64 - 72
• Main Authors: Ehrhardt, Nina M., Flöel, Agnes, Li, Shu-Chen, Lucchese, Guglielmo, Antonenko, Daria
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2024
• Subjects: Adult; Aged; Aged, 80 and over; Aging; Aging - physiology; Aging - psychology; Brain - physiology; Electroencephalography; Female; Gamma Rhythm - physiology; Humans; Male; Memory - physiology; Middle Aged; Oscillations; Phase-amplitude coupling; Sequence memory; Subsequent memory analysis; Theta Rhythm - physiology; Young Adult; Aging; Oscillations; Phase-amplitude coupling; Sequence memory; Subsequent memory analysis
• ISSN: 0197-4580; 1558-1497; 1558-1497
• DOI: 10.1016/j.neurobiolaging.2024.04.001

Sequence memory is subject to age-related decline, but the underlying processes are not yet fully understood. We analyzed electroencephalography (EEG) in 21 healthy older (60–80 years) and 26 young participants (20–30 years) and compared time-frequency spectra and theta-gamma phase-amplitude-coupling (PAC) during encoding of the order of visually presented items. In older adults, desynchronization in theta (4–8 Hz) and synchronization in gamma (30–45 Hz) power did not distinguish between subsequently correctly and incorrectly remembered trials, while there was a subsequent memory effect for young adults. Theta-gamma PAC was modulated by item position within a sequence for older but not young adults. Specifically, position within a sequence was coded by higher gamma amplitude for successive theta phases for later correctly remembered trials. Thus, deficient differentiation in theta desynchronization and gamma oscillations during sequence encoding in older adults may reflect neurophysiological correlates of age-related memory decline. Furthermore, our results indicate that sequences are coded by theta-gamma PAC in older adults, but that this mechanism might lose precision in aging. •Sequence memory, an important aspect of episodic memory, declines in healthy aging.•Lower theta and higher gamma activity in encoding of correct trials in young adults.•No subsequent memory effect in oscillatory brain activity in healthy older adults.•Theta phase modulates gamma amplitude to code for item position in older adults.