A Brain Connectivity Toolbox for Functional Near-Infrared Spectroscopy Data.

Functional near-infrared spectroscopy (fNIRS) is a promising and noninvasive optical functional neuroimaging method, and can also be a useful method in brain network researches. Functional connectivity and effective connectivity are two important analysis methods in brain connectionism. The available toolkits have greatly facilitated the preprocessing of fNIRS data and the task activation analysis. Nevertheless, toolkits that can assess brain activation and functional and effective connectivity simultaneously are still lacking at present. Here, we developed a brain connectivity toolbox for fNIRS data called fNIRS_AT with MATLAB. This toolbox includes the main functions of fNIRS data preprocessing, graphic plot, brain connectivity calculation, and statistical analysis. In the module of data preprocessing, NIRS light intensity can be converted into hemodynamic parameters using the differential pathlength factor (DPF) method, and the DPF values could be adjusted according to the light source wavelength and the subject's age. In the module of brain connectivity calculation, small-world properties and Granger causality are included. The brain activation and connectivity results can be statistically analyzed in the toolbox. Through the friendly graphical user interface, fNIRS_AT allows researchers to perform brain activation and connectivity analysis in an easy and flexible way. This software package will facilitate the application of NIRS in brain connectivity.