The prefrontal cortex (PFC) has been recognized as one of the most crucial brain regions responsible for cognitive control, thoughts, and actions. Advanced functional imaging has provided tools needed for the sensitive assessment of functional brain activities and also functional abnormalities in various brain regions. Functional near-infrared spectroscopy (fNIRS) is a highly promising neuroimaging modality that provides an efficient way to continuously monitor changes in blood oxygenation in the brain. Functional biomarkers validated and measured from fNIRS data have provided reliable and predictive information on various brain functional disorders. However, selecting optimum biomarkers from a set of hemodynamic features can be extremely challenging. Here, we focus on functional biomarkers driven from fNIRS data and advanced multivariate analysis used to extract those biomarkers. We introduce …