Estimation of bidirectional information flow in the human brain from evoked potentials by use of dipole tracing method

It is important to know the information flow between active regions in the brain for the elucidation of the information processing mechanism and for disease detection in the human brain. In this paper, at first, we estimate dipoles (via 3-layered concentric spherical model, 2-dipole estimation) from evoked potentials. Secondary, using derived 2 dipole locations and moments as loci and quantities of brain activities, we analyze the information flow between the two time-series of the 1st and the 2nd dipole moments by use of a time-series analysis method based on the directed transformation. We obtain bidirectional information flows between the neuronal activities localized in 3D space of the brain with respect to somatosensory evoked potentials measured with 21 electrodes arranged according to the international 10-20 standard by electrical stimulations on the median nerve of the right hand.