ELECTROPHYSIOLOGICAL ACTIVITY ESTIMATION METHOD

An electrophysiological activity estimation method is used to estimate active areas of a selected part of a living body (e.g., human brain). Based on electromagnetic field distribution measured on a surface of the selected part of the living body as well as its shape, the method assumes each equivalent current dipole as a source of electromagnetic field distribution. At first, grid points are created to cover the selected part of the living body (e.g., head). Using the pseudoinverse, the method performs estimation of dipole distribution for equivalent current dipoles. Then, the equivalent current dipoles are subjected to sorting based on a priority order. An evaluation function (e.g., structural risk) is calculated in accordance with a square error between the measured electromagnetic field distribution and a theoretical value of electromagnetic field distribution caused by the equivalent current dipole, as well as a number of measuring points and a number of equivalent current dipoles. Estimation and calculations are repeated while changing a number of equivalent current dipoles in accordance with the priority order. Then, noise distribution is estimated in response to a minimum value of the evaluation function. So, the dipole distribution is estimated using the noise distribution. Thus, it is possible to obtain estimation results which are represented by a direction and magnitude of the equivalent current dipole as well as an appropriate number of equivalent current dipoles.