Electromagnetic field stimulation modulates working memory and cortical alpha oscillations in healthy adults

Electromagnetic fields (EMFs) have been shown to modulate neural activity, yet their specific effects on memory, particularly the distinction between working memory and short-term recall, remain unresolved. This study examined whether patterned EMF exposure influences these domains, using the WAIS-IV Digit Span Forward (DSF) and Digit Span Backward (DSB) subtests. Ninety-eight healthy volunteers were randomly assigned, in a between-subjects design, to one of four conditions: Theta-Burst (five-pulse bursts at 100 Hz), Theta-Gamma (mimicking theta–gamma coupling in hippocampal networks), 40 Hz gamma stimulation, or sham stimulation. Fields were applied for 30 min in one of three spatial configurations: unilaterally over the left hemisphere, unilaterally over the right hemisphere, or bilaterally over the temporal lobes. Theta-Burst EMF reduced working memory performance on the DSB task and was accompanied by increased high-alpha (10–12 Hz) activity in the left inferior frontal gyrus and a whole-brain effect centered on the right superior frontal gyrus. In contrast, Theta-Gamma EMF reduced DSF performance without detectable EEG changes. These findings indicate that EMF effects on memory are frequency- and pattern-specific, selectively altering behavior and, in some cases, underlying neural activity. Optimizing stimulation parameters may allow such fields to be harnessed for cognitive enhancement or targeted neuromodulation.