Tensor decomposition exploiting structural constraints for brain source imaging

The separation of Electroencephalography (EEG) sources is a typical application of tensor decompositions in biomedical engineering. The objective of most approaches studied in the literature consists in providing separate spatial maps and time signatures for the identified sources. However, for some applications, a precise localization of each source is required. To achieve this, a two-step approach has been proposed. The idea of this approach is to separate the sources using the canonical polyadic decomposition in the first step and to employ the results of the tensor decomposition to estimate distributed sources in the second step, using the so-called disk algorithm. In this paper, we propose to combine the tensor decomposition and the source localization in a single step. To this end, we directly impose structural constraints, which are based on a priori information on the possible source locations, on the factor matrix of spatial characteristics. The resulting optimization problem is solved using the alternating direction method of multipliers, which is incorporated in the alternating least squares tensor decomposition algorithm. Realistic simulations with epileptic EEG data confirm that the proposed single-step source localization approach outperforms the previously developed two-step approach.