Transcranial Magnetic Stimulation (TMS) is a tool to stimulate, modulate, and interrupt brain activity. It is often seen (and used) as a crude, non-specific, tool. But it doesn’t have to be, shows Vanessa Johnen in a new paper in eLife. By stimulating two regions in a pair-wise fashion, exactly how they also interact naturally, you can boost or dampen their interaction for hours afterwards. Here we show that this paired-associative stimulation leads to changes in functional connectivity as measured using fMRI. The modulation of functional connectivity is strong between the two stimulated regions, but also extends further affecting connected systems. For example, if the local circuit is boosted, so are directly connected non-stimulated regions, while connectivity in competing circuits is actually dampened.