Local Polynomial Estimate of Surface Laplacian.

This paper describes a method for estimating the surface Laplacian of brain potentials. The method consists of two steps: local surface approximation by its tangent plane and local polynomial fitting. Compared to previous methods for estimating surface Laplacian, this method has some new features. First, it can estimate the surface Laplacian at any point of the scalp, including the locations of the peripheral electrodes. Secondly, it estimates the brain potential and the surface Laplacian at any point simultaneously. This reduces the risk of error propagation, which occurs when the brain potential is interpolated first and the surface Laplacian is then computed based on the interpolated brain potential. Finally, the method automatically adapts to noisy data by using more or less measurements at neighboring electrodes based on estimated noise level. Simulations suggest that this method is effective. Application to event-related potentials are also presented. [ABSTRACT FROM AUTHOR]