Schizophrenia--a disorder of the corollary discharge systems that integrate the motor systems of thought with the sensory systems of consciousness.

BACKGROUND: In spite of intensive research, no causal anatomical lesion has been found in schizophrenia. It may instead be caused by malfunctioning circuits in the corollary discharge, feed forward (CD-FF) systems of thought. AIMS: To integrate with the CD-FF hypothesis recent data showing that subcortical motor systems participate in thinking.
METHODS: We review CD-FF concepts in relation to recent evidence that 'motor' brain structures participate in cognitive processing.
RESULTS: Malfunctioning of CD-FF systems that integrate thinking and consciousness could produce auditory hallucinations, delusions and disorganised thought.
CONCLUSIONS: We hypothesise that the pathophysiology of schizophrenia lies in integrative circuits of basal ganglia, thalamus and frontal cortex. Fruitful research directions would include elucidation of CD-FF circuits at even higher brain levels, the behaviour of these circuits during dreaming, and their responses to late maturational events including synaptic elimination.