Habituation of the auditory evoked field component N100m in male patients with schizophrenia

The auditory evoked field (AEF) component N100m represents the most promine nt and stable peak of the AEF, and its alterations in patients with schizop hrenia are atl extensive topic of neuropsychiatric research. In our current study, the degree of N100m habituation was investigated in 20 male schizop hrenics and 19 healthy male controls. Participants were stimulated monaural ly with 270 trials of 1000 Hz tones separated by an interstimulus interval between 800 1800 ms. The trial sample of the bilaterally recorded AEF was s eparated into three consecutive blocks of 90 trials and these blocks were c ompared with each other. The mean global field power (MGFP) of the N100m de creased on average 9.1% from the first to the third trial block, while the N100m latency was increasing. The analyses of the influence of habituation revealed a systematic change of dipole location in inferior-superior direct ion, mainly in the left hemisphere. This habituation effect was found to be the same for both groups. The groups also did not differ in the N100m late ncy increase and MGFP decrease, except for one parameter. The right-hemisph eric MGFP decrease from the first to second block was found to be more pron ounced in patients compared to controls. However, this difference was relat ed to medication with clozapine, Overall, the habituation behaviour of the N100m seems to be undisturbed in schizophrenic patients. (C) 2000 Elsevier Science Ltd. All rights reserved.