title: Influence of observing another person's action on self-generated performance in schizophrenia.
abstract: BACKGROUND
  Observing another person's action influences the execution of one's own action via the mirror neuron system. However, the ability to control the effect of such action observation on one's voluntary action has not been investigated. The aim of this study was to elucidate the influence of observing another's action on own voluntary movement in patients with schizophrenia.
  
  
  METHODS
  Fifteen patients with schizophrenia and 15 healthy age-matched controls participated in this study. Subjects were asked to perform a gripping task at 50% of their maximal voluntary force (MVF), whereas simultaneously watching others performed the same task with a different grip force (0%, 50% and 100% MVF).
  
  
  RESULTS
  The healthy controls applied a constant grip force under each condition. In patients with schizophrenia, the grip force was significantly reduced during viewing the gripping of others at 50% MVF compared to during viewing other's gripping at 0% and 100% MVF. The score of the Brief Psychiatric Rating Scale (BPRS) and the Scale for the Assessment of Positive Symptoms were correlated with the fluctuation in grip force among the action observation conditions.
  
  
  CONCLUSIONS
  Patients with schizophrenia might have difficulty controlling the influence of action observation on self-generated performance.
authors.affiliation: a Department of Occupational Therapy , Chubu University , Kasugai , Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Minoru
authors.initials: M
authors.lastname: Hoshiyama
mesh_terms: D000328:Adult; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D059167:Mirror Neurons / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012559:Schizophrenia / Q000503:physiopathology*
keywords: action observation; efference copy; mirror neuron; schizophrenia; self-generated action