We acquired all fNIRS data with a commercial continuous-wave NIRS system (NIRScout, NIRx Medical Systems, New York). The optical probe contained 16 sources at two different wavelengths (LEDs centered at 760 and 850 nm,
light power emission for each) and 16 detectors. This configuration enabled the use of 32 source–detector combinations (i.e., channels) at 3 cm, and two source–detector pairs at 0.8 cm (short channels). Data were acquired at 7.8 Hz.
The probe design was arranged to be sensitive to the primary regions related to language and speech in the frontal, temporal, and parietal lobes. We positioned one short channel in each brain hemisphere. The short-channel data enabled us to regress out extracortical contributions hemispherically. To secure the optodes on the heads of the subjects, we used a 10–20 standard cap from NIRx Medical Systems.
58 (
link) We digitized the position of all optodes using a commercial digitizer (
Fastrack, Polhemus, Colchester, Vermont) for better accuracy concerning the location of each source and detector.
Figure 1(a) shows a sensitive profile for the probe, which was obtained from Monte Carlo simulations through the AtlasViewer package.
59 (
link)
Novi S.L., Roberts E., Spagnuolo D., Spilsbury B.M., Price D.C., Imbalzano C.A., Forero E., Yodh A.G., Tellis G.M., Tellis C.M, & Mesquita R.C. (2020). Functional near-infrared spectroscopy for speech protocols: characterization of motion artifacts and guidelines for improving data analysis. Neurophotonics, 7(1), 015001.