Transcranial Random Aperiodic Stimulation Improves Working Memory Precision.

Aperiodic neural activity - historically dismissed as noise - is independently modulated from neural oscillations during visual working memory maintenance. In the context of aging, "flatter" trait aperiodic activity is associated with poorer visual working memory performance. Here, we causally test the role of aperiodic neural activity in visual working memory in younger adults. We introduce a novel noninvasive neurostimulation method - transcranial random aperiodic stimulation (tRAS) - to causally manipulate aperiodic activity to be either steeper or flatter. In a randomized, double-blind, placebo-controlled, crossover neurostimulation design (n = 30), we show that online noninvasive tRAS improves visual working memory precision when aperiodic activity is causally steepened. Our novel stimulation method paves the way for causal studies of non-oscillatory, aperiodic activity in human cognition, aging, and disease.