title: Exploring psychotic symptoms: a comparison of motor related neuronal activation during and after acute psychosis.
abstract: BACKGROUND
  Delusions and hallucinations are classic positive symptoms of schizophrenia. A contemporary cognitive theory called the 'forward output model' suggests that the misattribution of self-generated actions may underlie some of these types of symptoms, such as delusions of control - the experience of self-generated action being controlled by an external agency. In order to examine the validity of this suggestion, we performed a longitudinal functional magnetic resonance imaging (fMRI) study examining neuronal activation associated with motor movement during acute psychosis.
  
  
  METHODS
  We studied brain activation using fMRI during a motor task in 11 patients with schizophrenia and 9 healthy controls. The patient group was tested at two time points separated by 6-8 weeks.
  
  
  RESULTS
  At initial testing, the patient group had a mean Positive and Negative Syndrome Scale score of 56.3, and showed significantly increased activation within the left inferior parietal lobe (IPL) compared to controls. Patients reported significantly decreased positive symptoms at 6-8 week followup and IPL activation had returned to normal. Our results demonstrate that first-rank positive symptoms are associated with hyperactivation in the secondary somatosensory cortex (IPL).
  
  
  CONCLUSIONS
  These findings lend further credence to the theory that a dysfunction in the sensory feedback system located in the IPL, and which is thought to underlie our sense of agency, may contribute to the aetiology of delusions of control.
authors.affiliation: Institute of Psychiatry, De Crespigny Park, London, UK.
authors.forename: Luke Sheridan
authors.initials: LS
authors.lastname: Rains
authors.forename: Gregory
authors.initials: G
authors.lastname: Fallica
authors.forename: Owen
authors.initials: O
authors.lastname: O'Daly
authors.forename: James
authors.initials: J
authors.lastname: Gilleen
authors.forename: Vincent
authors.initials: V
authors.lastname: Giampetro
authors.forename: Lucy
authors.initials: L
authors.lastname: Morley
authors.forename: Sukhi
authors.initials: S
authors.lastname: Shergill
mesh_terms: D000328:Adult; D000339:Affect; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003463:Cues; D003702:Delusions / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D059907:Functional Neuroimaging; D006212:Hallucinations / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D011618:Psychotic Disorders / Q000503:physiopathology*; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*