Scalp coupling index

Definition: Scalp coupling index (SCI) is a signal-to-noise ratio measurement computed as the zero-lag cross-correlation between the normalized raw intensity signals at two wavelengths, filtered in the cardiac frequency band. In fNIRS analysis, the SCI is applied in the context of signal quality assessment on a channel-by-channel basis. Channels below a certain, pre-defined threshold are thus classified as channels with insufficient data quality and excluded from further analysis.

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References:

https://doi.org/10.1364%2FBOE.7.005104

Related terms: Signal Quality Assessment, Peak Spectral Power