Method for Locating Sources of Human Alpha Activity

摘要: Alpha activity is commonly defined as electrical fluctuations between 8 and 13 Hz that can be detected on the occipital scalp are attenuated by visual stimuli. While projections from brain stem play a role in its generation (c.f. Steriade Llinas, 1988), evidence for cortical origin of these signals has been obtained studies potentials at various depths within cortex animals. Lopes da Silva van Leeuwen (1978) suggest alpha sources originate different epicenters which spreads across several directions. Previous magnetic humans covariance EEG recordings with single sensor indicate deep lobe (Carelli et al., 1983). Studies four-sensor system (Vvedensky, Ilmoniemi, Kajola, 1986) there time series rhythm lasting typically 1 sec during oscillation period constant. We call spindles, whether or not occurring sleeping state. Williamson, Hostetler (1988) using 14-sensor found field pattem spindle appears relatively stable, indicating source specific configuration neurons. Moreover, an analysis time-invariant spatial based 14-dimensional signal space indicates it possible to distinguish most observed spindles. In other words, human represented spindles generated large number, possibly continuum, configurations. introduce term alphon neuronal excitation producing spindle. The purpose present study develop technique determine locations alphons characterize orientation strength their equivalent current dipole moments.