Résumé
OBJECTIVES: While most neurological models of schizophrenia have focused on cerebral functions, cerebellar abnormality, especially in cerebellar vermis has been repeatedly reported in schizophrenic patients from brain imaging and lesion studies. And cerebellar vermis has been implicated for adaptive control of saccadic eye movements, which has not been studied in schizophrenics to our knowledge. METHOD: We investigated saccadic adaptation using double-step paradigm in 5 patients with a DSM-IV diagnosis of schizophrenia and 5 age and sex-matched normal controls. Gaze and head movements were recorded with scleral search coil method in head-free condition. RESULTS: Time course of adaptation in schizophrenics was similar to that of normal control but it never reached to the complete level of adaptation seen in control, and accordingly gaze gain (gaze amplitude/target amplitude) was low even after 600 adaptive trials. Head contribution to gaze saccade was relatively low and time to peak head velocity was longer in schizophrenics. CONCLUSIONS: Our results suggested that schizophrenic patients used a different strategy of gaze control and some schizophrenics might have cerebellar abnormality. Variability across patients in adaptation parameters need to be further investigated in combination with cerebellar volumetry. This study was supported by "In-san Schizophrenia Research Grant" from the Research Institute of Korean Neuropsychiatric Association in 1997.