The neurosomatic technique, also colloquially known as a neural drain, was a medical procedure on Tilonus IV.
In 2369, this procedure was used by Suna when he attempted to extract information from Starfleet officer William T. Riker's memory. During the procedure, Riker's mind created a defense mechanism which resisted the technique. His unconscious mind latched onto elements from Riker's real life – the mission preparation, the play Frame of Mind – in an attempt at keeping him grounded and sane. The technique caused long-term memory loss for Riker, until Beverly Crusher repaired the damage. (TNG: "Frame of Mind")