Wireless intraoperative real-time monitoring of neurotransmitters in humans

For decades, Fast Scan Cyclic Voltammetry (FSCV) has been an established method for investigating neurochemical changes in animal models. Various neurotransmitters have been monitored successfully in vivo with high spatial and temporal resolution including dopamine, norepinephrine, adenosine, and serotonin. While FSCV has already provided myriad insights into physiological and pathophysiological neurochemical signaling in the brain, this technique has traditionally been restricted to small animal models. After initial implementations in large animal models, our group and others have recently translated FSCV successfully into humans, showing intraoperative neurochemical monitoring of dopamine and adenosine release in the human brain of patients undergoing deep brain stimulation (DBS) surgery for Parkinson's disease or essential tremor. In this review, we provide an overview of the recent advances in human electrochemistry and current state-of-the-art approach for performing neurochemical recordings in the intraoperative setting in humans. Furthermore, we describe pertinent technological developments such as the WINCS (Wireless Instantaneous Neurotransmitter Concentration Sensing) system and its successor WINCS-Harmoni, a next generation device capable of combining brain stimulation with real-time neurochemical recording in vivo. Finally, we discuss the future potentials of human electrochemistry to advance the understanding of the neurophysiology of the central nervous system, pathological neurochemical changes, and mechanisms of DBS. It is important to note that human neurochemistry is still in its infancy and numerous critical challenges will have to be addressed over the next decades. However, these preliminary studies have shown that DBS surgery offers a unique window of opportunity for performing neurochemical recordings that would be beyond the scope of preclinical research. This technique may thereby provide unprecedented insights into human brain chemistry and myriad neurological and psychiatric conditions.