An online database of infant functional near infraRed spectroscopy studies: a community-augmented systematic review

Until recently, imaging the infant brain was very challenging. Functional Near InfraRed Spectroscopy (fNIRS) is a promising, relatively novel technique, whose use is rapidly expanding. As an emergent field, it is particularly important to share methodological knowledge to ensure replicable and robust results. In this paper, we present a community-augmented database which will facilitate precisely this exchange. We tabulated articles and theses reporting empirical fNIRS research carried out on infants below three years of age along several methodological variables. The resulting spreadsheet has been uploaded in a format allowing individuals to continue adding new results, and download the most recent version of the table. Thus, this database is ideal to carry out systematic reviews. We illustrate its academic utility by focusing on the factors affecting three key variables: infant attrition, the reliability of oxygenated and deoxygenated responses, and signal-to-noise ratios. We then discuss strengths and weaknesses of the DBIfNIRS, and conclude by suggesting a set of simple guidelines aimed to facilitate methodological convergence through the standardization of reports

Proportion of infants excluded as a function of number of optodes.

<p>Number of optodes is totaled over sources and detectors. Each letter indicates an entry, coding for the system: ‘i’ stands for Hitachi, ‘a’ for Hamamatsu, and ‘x’ for all other systems. The boxplot on the right bottom panel represents the exact same data, collapsing into two categories: less than 20 optodes, and more than 20 optode.</p

Guidelines for infant fNIRS reporting.

<p>Items in 'strongly recommended' are necessary to achieve basic standardization and thus we should strive to report them; those in 'additional' would also be included for completeness.</p

Variables coded.

<p>Variables coded.</p

Age groups studied.

<p>The upper boundary of the histogram has been fixed to exclude the outlier at 27 months.</p

Number of optodes as a function of year.

<p>Number of optodes is totaled over sources and detectors.</p