Reduction of physiological interference in optical functional neuroimaging using eigenvector-based spatial filtering

Diffuse optical imaging is an effective technique for noninvasive functional brain imaging. However these measurements also respond to systemic hemodynamic fluctuations which may obscure or overwhelm the desired stimulus-evoked response. In this paper, we use the spatial behavior of measured baseline signals to identify interference subspaces and project out components of the data which lie in this subspace. We assume that systemic components will be more global spatially, with higher energy than the signals of interest. Through this spatial filtering, we can obtain a more localized response, and improved correlation coefficient (CC) maps. We report tests in data from 2 human subjects.