The dimensional complexity of the P3 event-related potential: area-specific and task-dependent features

Appropriate methods are needed for the study of the non-linear properties of the nervous system. The correlation dimension, as expressed by the effective point correlation dimension (PD2eff), was used in this study for the analysis of the dimensional complexity of event-related potentials. The ERPs were recorded at Fz, Cz and Pz in an auditory oddball paradigm in which 'easy' and 'difficult' sensory discrimination tasks were applied. The PD2eff was calculated from each EEG epoch used in the process of ERP averaging. The PD2eff significantly decreased during the ERPs in which the P3-component appeared, and this reduction showed area-specific and task-specific patterns. The area-specific PD2eff changes indicated distinctive functional features of the frontal areas in this task. The magnitude of the PD2eff change was found to depend on the degree of task difficulty. Implications of the findings related to theories on the functional significance of the P3-wave in information processing are discussed.