Modern neuro- and psychophysiological findings on commissurotomized ("split-brain") patients seem to confirm psychoanalytic theories. Twelve commissurotomized patients and one patient who had a right hemispherectomy showed an impoverishment of dreams, fantasies and symbolization. This might have been due to an interruption of the preconscious stream between the two hemispheres, which causes a separation of word-presentations from thing-presentations, as well as to a predominance of a feedback-free primary process in the right hemisphere. The similarity in operational thinking of psychosomatic and split-brain patients leads the author to hypothesize a "functional commissurotomy" in cases of severe psychosomatic disturbances.