ABSTRACT
ObjectiveTo explore gamma resonance signals in acute medication-free schizophrenics,and the effects of antipsychotics on gamma activity.MethodsSchizophrenia patients( n=56) and normal controls ( n =18 ) underwent auditory steady-state event-related potential testing and were evaluated of their psychopathic syndromes with the positive and negative syndrome scale (PANSS) before and after 8 weeks of medication with oral chlorpromazine or clozapine.Click trains varying in rate of stimulation 40 Hz were presented; EEG-evoked power and intertrial phase synchronization were obtained in response to stimulation frequency.ResultsSchizophrenic patients showed reduced evoked power( Fz:( 5.08 ± 1.48) μV2 vs (6.91 ± 1.64) μV2 ; Cz:(4.70 ± 2.03 ) μV2 vs ( 6.93 ± 1.43 ) μV2 ; P ＜ 0.01 ) and a tendency of reduction in phase synchronization ( Fz:0.14 ± 0.04 vs 0.13 ± 0.04,P =0.051 ; Cz:0.18 ± 0.06 vs 0.17 ± 0.06,P =0.056) in response to 40 Hz stimulation.However significant correlations were not observed between oscillatory responses and clinical parameters in schizophrenic patients.There were no significant differences of gamma power and ITC in patients before and after chlorpromazine or clozapine administered.ConclusionSchizophrenia patients have deficits in the power and coherent of gamma oscillations,and can not be normalized by medication with antipsychotics.