Light up ADHD: I. Cortical hemodynamic responses measured by functional Near Infrared Spectroscopy (fNIRS): Special Section on "Translational and Neuroscience Studies in Affective Disorders" Section Editor, Maria Nobile MD, PhD. This Section of JAD focuses on the relevance of translational and neuroscience studies in providing a better understanding of the neural basis of affective disorders. The main aim is to briefly summarise relevant research findings in clinical neuroscience with particular regards to specific innovative topics in mood and anxiety disorders.

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by deficits in cognitive and emotional self-control. Optical technique acquisitions, such as near infrared spectroscopy (NIRS), seem to be very promising during developmental ages, as they are non- invasive techniques and less influenced by body movements than other neuroimaging methods. Recently, these new techniques are being widely used to measure neural correlates underlying neuropsychological deficits in children with ADHD.

METHODS: In a short series of articles, we will review the results of functional NIRS (fNIRS) studies in children with ADHD. The present brief review will focus on the results of the fNIRS studies that investigate cortical activity during neuropsychological and/or emotional tasks.

RESULTS: According to the reviewed studies, children and adolescents with ADHD show peculiar cortical activation both during neurological and emotional tasks, and the majority of the reviewed studies revealed lower prefrontal cortex activation in patients compared to typically developmental controls.

LIMITATIONS: a consistent interpretation of these results is limited by the substantial methodological heterogeneity including patients' medication status and washout period, explored cerebral regions, neuropsychological tasks, number of channels and sampling temporal resolutions.

CONCLUSIONS: fNIRS seems to be a promising tool for investigating neural substrates of emotional dysregulation and executive function deficits in individuals with ADHD during developmental ages.