Schizophrenia is associated with structural changes in the brain but it is not clear whether the changes are localized. Studies in Manchester and elsewhere have reported abnormalities in biochemical markers of glutamate- and GABA-containing neurones in post-mortem brains from schizophrenic patients. The abnormalities occur in the ventral frontal cortex and anterior temporal lobe. It is suggested that these regions of the brain specifically encode information about social communication – language, gesture and facial expression. Many of the symptoms of schizophrenia become neuropsychologically understandable when seen as disturbances of social communication. In this and the following papers, experimental tests of this hypothesis are described.