It was first suggested that disordered proprioception was a core feature of
schizophrenia by Sandor Rado in 1953. Using a recently designed
proprioceptive event-related potential paradigm based on a change of load,
we studied 12 unmedicated male out-patients with schizophrenia and 24
controls. In the patients, the early contralateral parietal activity was
delayed and later central activity had increased amplitude, but gating was
unaffected. The results could be understood within the ‘deficiency of
corollary discharge’ model of schizophrenia but not within the ‘filtering’
theory. Further studies, including psychiatric controls, are necessary to
verify the specificity of the abnormality.