Brainshock (also written as "BrainShock") is a PSI ability in all three titles of the Mother video game series. It works on a single enemy, or all enemies, depending on the power level, and causes the affected target to feel strange, which may cause them to attack their allies. Brainshock is learned in Mother by Ana, in EarthBound by Poo, and in Mother 3 by Kumatora.
Despite the name, even enemies who probably don't have a brain (e.g. Screwloose) can still be affected by this.