On complex infomax applied to functional MRI data

Functional magnetic resonance imaging (fMRI) is a technique which produces complex data; however the vast majority of functional magnetic resonance imaging analyses utilize only magnitude images. In this paper, we derive a complex-valued independent component analysis (ICA) algorithm using the infomax approach which we then apply to fMRI analysis. Theoretical and empirical results demonstrate an improved sensitivity to functional changes when utilizing the complex data. Additionally, the complex infomax algorithm developed provides a powerful method for exploratory analysis of fMRI data.