Working memory revived in older adults by synchronizing rhythmic brain circuits

Understanding normal brain aging and developing methods to maintain or improve cognition in older adults are major goals of fundamental and translational neuroscience. Here, we show a core feature of cognitive decline - working memory deficits - emerges from disconnected local and long-range circuits instantiated by theta-gamma phase-amplitude codes in temporal cortex and theta phase synchronization across frontotemporal cortex. We developed a noninvasive stimulation procedure for modulating long-range theta interactions in adults aged 60–76 years. After 25 minutes of stimulation, frequency tuned to individual brain network dynamics, we observed a preferential increase in neural synchronization patterns and the return of sender-receiver relationships of information flow within and between frontotemporal regions. The end result was rapid improvement in working memory performance that outlasted a 50-minute post-stimulation period. The results provide insight into the physiological foundations of age-related cognitive impairment and contribute groundwork for future non-pharmacological interventions targeting aspects of cognitive decline.