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 mater 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 synapticelimination.