Psychosurgery is a subset of neurosurgery (surgery of the brain) intened to modulate the performance of the brain, and thus effect changes in cognition, with the intent to treat or alleviate severe mental illness. It was originally thought that by severing the nerves that give power to ideas you would achieve the desirable result of a loss of affect and an emotional flattening which would diminish creativity and imagination; the idea being that those are the human characteristics that are disturbed. Historically, the procedure typically considered psychosurgery, prefrontal leukotomy is now almost universally shunned as inappropriate, due in part to the emergence of less-invasive or less-objectionable methods of treatment such as psychiatric medication and modified electroconvulsive therapy. In modern neurosurgery however, more minimally invasive techniques like gamma knife irradiation and foremost deep brain stimulation have arisen as novel tools for psychosurgery.