Complexity analysis of functional near-infrared spectroscopy signals

The main hypothesis tested in this study is that cognitive activity causes a change in the complexity of functional near-infrared spectroscopy (fNIRS) signals. We calculated neural complexity (C_N) of fNIRS signals obtained during mental arithmetic task and monitored the time course of change in neural complexity. Considerable increases in neural complexity were observed during active periods of the experiment. This result indicates that statistical measures may play important roles in the efforts to detect brain activation by optical methods.