Scalp distribution of the dimensional complexity of the EEG and the P3 ERP component in stroke patients

The use of recently developed techniques allows the quantitative investigation of the non-linear properties of the electrical activity of the brain not only in basic but also in applied research. The point correlation dimension (PD2) was used in this study for the analysis of the electroencephalogram (EEG) recorded in patients with unilateral stroke caused by middle cerebral artery occlusion. The scalp distribution of the PD2 and that of the P3 event-related potential component was mapped and frequency spectra were calculated. Compared to normal controls, asymmetrical PD2 distribution was observed with low values on the side of the stroke, the extension of which depended on recording conditions (level of vigilance) and only partially corresponded to the region characterized by slow frequencies. In one case, ipsilateral reduction of the P3 wave was caused by a small subcortical stroke. The efficacy of the linear and non-linear methods in localizing brain pathology are evaluated and compared.