Figure 5.

Bubble plot to illustrate fNIRS use to monitor treatment-related brain activation in relation to symptom improvement across psychiatric studies (N = 47). The x-axis represents the number of studies reporting each combination of activation pattern and clinical link, while the y-axis categorizes the direction of fNIRS activation observed post-treatment: increased, decreased, mixed, or not reported. Each bubble is sized according to sample size category, ranging from single-subject designs to studies with over 100 participants. Bubble color indicates whether a link between fNIRS signal change and clinical improvement was reported (Yes = blue, No = red, Not reported = grey).