CORRELATION DIMENSION CHANGES ACCOMPANYING THE OCCURRENCE OF THE MISMATCH NEGATIVITY AND THE P3 EVENT-RELATED POTENTIAL COMPONENT

The aim of this study was to apply recently developed mathematical too ls of chaos theory to the analysis of event-related potentials (ERPs) recorded in paradigms in which the mismatch negativity (MMN) and the P 3 component appeared. A new method, the point correlation dimension (P D2i), was used for data analysis, which is more accurate than other al gorithms for the calculation of the correlation dimension (D2), which latter is a measure of the complexity of the generator(s) responsible for producing the analyzed time series, i.e., the EEG. ERPs were recor ded from Fz, Ct and Pt in 6 subjects. With respect to baseline, the PD 2i decreased significantly both during the event-related potentials in which the MMN and also in which the P3 was present, but the pattern a nd magnitude of this decrease was different between these two situatio ns. The pattern of PD2i changes during the occurrence of deviant stimu li eliciting the MMN suggests the presence of a frontal MMN generator. The conspicuous PD2i decrease during the occurrence of the P3 wave ma y support the ''context closure'' hypothesis concerning its functional significance.