title: Event-related changes of the prefrontal cortex oxygen delivery and metabolism during driving measured by hyperspectral fNIRS.
abstract: Recent technological advancements in optical spectroscopy allow for the construction of hyperspectral (broadband) portable tissue oximeters. In a series of our recent papers we have shown that hyperspectral NIRS (hNIRS) has similar or better capabilities in the absolute tissue oximetry as frequency-domain NIRS, and that hNIRS is also very efficient in measuring temporal changes in tissue hemoglobin concentration and oxygenation. In this paper, we extend the application of hNIRS to the measurement of event-related hemodynamic and metabolic functional cerebral responses during simulated driving. In order to check if hNIRS can detect event-related changes in the brain, we measured the concentration changes of oxygenated (HbO2) and deoxygenated (HHb) hemoglobin and of the oxidized state of cytochrome c oxidase, on the right and left prefrontal cortices (PFC) simultaneously during simulated driving on sixteen healthy right-handed participants (aged between 22-32). We used our in-house hNIRS system based on a portable spectrometer with cooled CCD detector and a driving simulator with a fully functional steering wheel and foot pedals. Each participant performed different driving tasks and participants were distracted during some driving conditions by asking general knowledge true/false questions. Our findings suggest that more complex driving tasks (non-distracted) deactivate PFC while distractions during driving significantly activate PFC, which is in agreement with previous fMRI results. Also, we found the changes in the redox state of the cytochrome C oxidase to be very consistent with those in the concentrations of HbO2 and HHb. Overall our findings suggest that in addition to the suitability of absolute tissue oximetry, hyperspectral NIRS may also offer advantages in functional brain imaging. In particular, it can be used to measure the metabolic functional brain activity during actual driving.
authors.affiliation: Department of Physics, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada; Medical Physics, Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Reyhaneh
authors.initials: R
authors.lastname: Nosrati
authors.affiliation: Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.
authors.forename: Kristin
authors.initials: K
authors.lastname: Vesely
authors.affiliation: Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada; Department of Surgery, Faculty of Medicine (Neurosurgery), University of Toronto, 27 King's College Cir, Toronto, ON, M5S, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto27 King's College Cir, Toronto, ON, M5S, Canada.
authors.forename: Tom A
authors.initials: TA
authors.lastname: Schweizer
authors.affiliation: Department of Physics, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada.
authors.forename: Vladislav
authors.initials: V
authors.lastname: Toronov
keywords: (170.2655) Functional monitoring and imaging; (300.0300) Spectroscopy