Rate of stimulation affects schizophrenia-normal differences on the N1 auditory-evoked potential

The present study examined how increasing the rate of steady-state stimulation affects schizophrenia-normal differences on the N1 auditory-evoked potential, an index of auditory integration. Dense-array EEG was recorded while schizophrenia and normal subjects heard 1 kHz tones amplitude modulated at 10, 20, 40, or 80 Hz. Spectral power across frequency and time was calculated. The typically lower N1 amplitude in schizophrenia, observed at the 10 Hz burst rate, increased to nearly equal that of normal individuals at 20 Hz. Unlike normal subjects, schizophrenia subjects' power at N1 failed to increase at the 40 and 80 Hz burst rates. These results suggest steady-state stimuli, up to a point, provide the extra information needed for schizophrenia patients to more efficiently integrate auditory information.