Fig 1. The effect of slow brain stimulation on different brain areas and memory performance.

Applying slow (1 pulse per second) rTMS over the left DLPFC (compared to the vertex at top of the head as control region) is associated with enhanced word memory performance (10% to 20% increase). Apart from the effect of rTMS on memory performance, prefrontal stimulation causes enhanced event-related beta suppression at the parietal cortex, a neural response known to be a correlate of memory encoding. However, a further follow-up investigation reveals that increased beta suppression is driven by a steeper slope of aperiodic (scale free) rather than periodic (oscillatory) activity, a feature that reflects a decreased excitation to inhibition ratio of neural electrical currents. DLPFC, dorsolateral prefrontal cortex; EEG, electroencephalogram; rTMS, repetitive transcranial magnetic stimulation.