Source localization of periodic sharp wave complexes using independent component analysis in sporadic...

Patients with Creutzfeldt-Jakob disease (CJD) show periodic sharp wave complexes (PSWCs) on electroencephalography (EEG) during the course of their illness. However, the source location of PSWCs and their pathophysiological mechanism remain unclear. Six patients with sporadic CJD who showed typical PSWCs on EEGs were selected for the study. Sixty epochs, each spanning the period from -0.25 to +0.25 s after the negative maximum of a typical PSWC, were selected for analysis in each patient. The EEG data matrix was decomposed using an independent component analysis based on a simple, neural network algorithm that can blindly separate mixtures of independent sources, using information maximization. The separate independent components were subjected to dipole source localization using a single dipole model. Three to seven independent components responsible for the PSWCs seen in CJD were identified. The EEG recording reconstructed from the selected independent components accounted for more than 80% of the variance in the original recording. All patients showed dipole sources responsible for the PSWCs of CJD in both the cortical and subcortical deep gray matter. In five of six patients, the dorsolateral and medial frontal cortices were the cortical sources of the PSWCs. Four patients showed dipole sources in the caudate and/or lentiform nucleus. In three patients, the dipole source was localized in the thalamus. These findings suggest that basal ganglia and thalami, as well as frontal cortices, are involved in generating PSWCs in CJD.