Hallucination in schizophrenia. Coloured Positron Emission Tomography (PET) brain scan of a schizo- phrenic male patient aged 23 during hallucination. The left side of the brain is seen. Highlighted in orange are areas of brain activity. During hallu- cination the patient saw coloured heads which spoke to him. Visual (at right) & auditory (upper centre) areas of brain are active confirming the patient has seen and heard" an hallucination. Schizophrenia is characterised by deluded thought, hallucination and depression. Brain activity (orange) detected by PET scanning, has been super- imposed on a white MRI image of the human brain."