Systems theory
Systems theory, in this context, may be regarded as an extension of Braid's original conceptualisation of hypnosis as involving "the brain and nervous system generally". Systems theory considers the nervous system's organisation into interacting subsystems. Hypnotic phenomena thus involve not only increased or decreased activity of particular subsystems, but also their interaction. A central phenomenon in this regard is that of feedback loops, which suggest a mechanism for creating hypnotic phenomena.