Near-Infrared Spectroscopy as a New Tool for Neurofeedback Training: Applications in Psychiatry and Methodological Considerations

Abstract

Over the past decades, functional near-infrared spectroscopy (fNIRS) has become a valuable tool in the online assessment of brain function in psychological and neuropsychiatric research. Recently, fNIRS has also been employed in the context of neurofeedback (NF), with pilot studies indicating that hemodynamic responses can be deliberately regulated and that neuroplastic changes occur over the course of several training sessions. This review article provides a comprehensive overview of the recent implementation and development of fNIRS as an NF tool; specifically, we will outline initial studies in healthy participants as well as children and adults with attention deficit hyperactivity disorder and describe new protocols aimed at reducing auditory verbal hallucinations (schizophrenic patients) and anxiety symptoms (patients with social anxiety disorder), respectively. Finally, we will discuss recent methodological developments and concerns as well as potential future perspectives. We conclude that fNIRS is a useful tool for conducting NF, especially in terms of multi-session training. However, methodological details need to be considered when designing fNIRS-based NF studies, and future protocols should aim at training broader network structures and implementing implicit training protocols. Finally, future studies should focus not only on (clinical) effects of fNIRS-based NF, but also on the underlying mechanisms and activity changes in extended brain networks.