Wavelet analysis of the frontal auditory evoked potentials obtained in the passive oddball paradigm in healthy subjects and schizophrenics.

The goal of the present study was to apply the oscillatory brain dynamics model to the structural and quantitative analysis of neurocognitive functions considered as a potential marker of schizophrenia. This was achieved in tests of the detection of auditory events deviating in the regular auditory stream (oddball paradigm, MMN effect). It was hypothesized that the post-stimulus peaks of the oscillation power localized in post-stimulus time in the definite EEG oscillators represented neuro-electrical 'events' evoked in the specific neuronal nets characterized by this oscillation frequency band. We suggest that the time-frequency destination of these events related to the activation of the functional neuronal nets could be used for the determination of specific neurocognitive functions. Thus it was an attempt to distinguish the different neuro-functional parts of auditory processing and to compare these results between healthy subjects and patients with schizophrenia. The present results demonstrate the significant difference between the frontal averaged EEG oscillatory dynamics in healthy subjects and patients with schizophrenia related to neurocognitive function marked by the MMN and orienting response N200/P300a.