Photo provided by Boston University shows a cap that administers electrical stimulation and monitors brain waves for a visual working memory test at one of the school's laboratories. A study released on Monday, April 8, 2019, finds that zapping the brains of people over 60 with a mild electrical current improved a form of memory enough that they performed like people in their 20s. https://medicalxpress.com/news/2019-04-brain-zaps-boost-memory-people.html
Alzheimer disease and related cognitive disorders typically involve accelerated age-related cognitive decline and are associated with deficits of working memory (short-term active storage of important information).
These deficits are linked to desynchronization of rhythmic activity between the prefrontal regions that evaluate information and the temporal regions that store it. To develop an intervention for this phenomenon, researchers conducted a series of experiments in 154 volunteers.
On a computer-based task, older, nondemented adults (ages, 60–76) had worse working memory than younger adults (ages, 20–29). These working-memory deficits were associated with uncoupling of frontotemporal theta (4–8 Hz) and left temporal theta-gamma (>25 Hz) phase amplitudes on electroencephalography.
The older group underwent 25 minutes of targeted high-definition transcranial alternating-current stimulation (HD-tACS) tuned to individual brain network dynamics. HD-tACS rapidly normalized the cortical-rhythm disruptions, restoring phase synchronization typical of younger adults. Phase coordination was associated with improvement in accuracy of working memory, and improved working memory and phase synchronization persisted to the end of the 50-minute poststimulation observations.
Reinhart RMG, Nguyen JA. Working memory revived in older adults by synchronizing rhythmic brain circuits. Nature Neuroscience 2019. https://doi.org/10.1038/s41593-019-0371-x
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 coupling 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 min 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 min post-stimulation period. The results provide insight into the physiological foundations of age-related cognitive impairment and contribute to groundwork for future non-pharmacological interventions targeting aspects of cognitive decline.
