Abstract
.Significance: The establishment of a light propagation analysis-based scalp-cortex correlation (SCC) between the scalp location of the source–detector (SD) pair and brain regions is essential for measuring functional brain development in the first 2 years of life using functional near-infrared spectroscopy (fNIRS).Aim: We aimed to reveal the optics-based SCC of 0-, 1-, and 2-year-olds (yo) and the suitable SD distance for this age period.Approach: Light propagation analyses using age-appropriate head models were conducted on SD pairs at 10-10 fiducial points on the scalp to obtain optics-based SCC and its metrics: the number of corresponding brain regions (), selectivity and sensitivity of the most likely corresponding brain region (MLCBR), and consistency of the MLCBR across developmental ages. Moreover, we assessed the suitable SD distances for 0-, 1-, and 2-yo by simultaneously considering the selectivity and sensitivity of the MLCBR.Results: Age-related changes in the SCC metrics were observed. For instance, the of 0-yo was larger than that of 1- and 2-yo. Conversely, the selectivity of 0-yo was lower than that of 1- and 2-yo. The sensitivity of 1-yo was higher than that of 0-yo at 15- to 30-mm SD distances and higher than that of 2-yo at 10-mm SD distance. Notably, the MLCBR of the fiducial points around the longitudinal fissure was inconsistent across age groups. An SD distance between 15 and 25 mm was found to be appropriate for satisfying both sensitivity and selectivity requirements. In addition, this work provides reference tables of optics-based SCC for 0-, 1-, and 2-yo.Conclusions: Optics-based SCC will be informative in designing and explaining child developmental studies using fNIRS. The suitable SD distances were between 15 and 25 mm for the first 2 years of life.
Highlights
In addition to MTG_R and ITG_R, other brain regions, the superior temporal gyrus (STG-R) and right temporal pole of the superior and middle temporal gyrus (TPOsup-R and TPOmid-R, respectively), were associated with T4, and their Lnorm;M increased as the SD distance increased
The photon measurement density function (PMDF) of the vertical SD pair set at fiducial point T4 is shown in Fig. S1 in the Supplementary Material
We found that the vertical SD pair at T4 was mainly correlated with the two brain regions, that is, MTG_R and ITG_R
Summary
The first two years of human life are characterized by the most dynamic growth in brain structures[1,2,3,4,5] and remarkable cognitive and behavioral changes.[6,7] Functional near-infrared spectroscopy (fNIRS; a list of abbreviations is provided in Table S1 in the Supplementary Material for the convenience of the reader) is an irreplaceable neuroimaging tool for studying early brain functional development, providing unprecedented opportunities for recording the hemodynamic NeurophotonicsDownloaded From: https://www.spiedigitallibrary.org/journals/Neurophotonics on 23 Dec 2021 Terms of Use: https://www.spiedigitallibrary.org/terms-of-useApr–Jun 2021 Vol 8(2)Cai et al.: Correlating functional near-infrared spectroscopy with underlying cortical regions. . .response in awake, behaving infants because of its balanced temporal-spatial resolution and resilience to movement.[8,9,10,11] Notably, the Centers for Disease Control and Prevention defines 0- to 1-year-olds (yo) and 2- to 3-yo children as infants and toddlers, respectively, we have described 0- to 2-yo children as infants in this study for readability.Despite the suitability of fNIRS in infant studies, a major limitation of this technique is the inability of fNIRS data to provide structural information of the head tissue. The first two years of human life are characterized by the most dynamic growth in brain structures[1,2,3,4,5] and remarkable cognitive and behavioral changes.[6,7] Functional near-infrared spectroscopy (fNIRS; a list of abbreviations is provided in Table S1 in the Supplementary Material for the convenience of the reader) is an irreplaceable neuroimaging tool for studying early brain functional development, providing unprecedented opportunities for recording the hemodynamic Neurophotonics. In fNIRS studies, the scalp location where the SD pair is attached to its underlying brain region where the fNIRS signal originates should be mapped. We call this mapping the scalp-cortex correlation (SCC)
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