FC-NIRS: A Functional Connectivity Analysis Tool for Near-Infrared Spectroscopy Data

Figure 7

The experimental example for quality control of human brain data. (a) The time series of the hemoglobin concentration signals. A large fluctuation can be found at approximately 600 seconds. (b) The motion artifacts check. The window length is set to 2 s. The threshold is set to 5, which means that the values larger than five standard deviations from the mean are considered to be motion artifacts. (c) The SNR check. Channel 13 and channel 28 both have very low SNRs, which are computed as the mean signal intensity divided by the SD of the signal intensity over time compared with the other channels, and the corresponding signal correlation is very low. The low SNR of two channels can be caused by poor contact between the optodes and the scalp.