title: Functional frequency-domain near-infrared spectroscopy detects fast neuronal signal in the motor cortex.
abstract: Millisecond changes in the optical properties of the human brain during stimulation were detected in five volunteers using noninvasive frequency-domain near-infrared spectroscopy. During a motor stimulation task we found highly significant signals, which were directly related to neuronal activity and exhibited much more localized patterns than the slow hemodynamic signals that are also detected by the near-infrared method. We considerably reduced the noise in the instrumental system and improved data analysis algorithms. With the achieved signal-to-noise ratio, single subject measurements were feasible without the requirement of particularly strong stimuli and within a reasonable period of measurement of 5 min at a mean signal-to-noise ratio of 3.6. The advantage of this noninvasive technique with respect to electrical recording is that it is able to detect neuronal activity with the relatively high spatial resolution of 8 mm.
authors.affiliation: Laboratory for Fluorescence Dynamics, Department of Physics, University of Illinois at Urbana-Champaign, 61801-3080, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Wolf
authors.forename: Ursula
authors.initials: U
authors.lastname: Wolf
authors.forename: Jee H
authors.initials: JH
authors.lastname: Choi
authors.forename: Rajarsi
authors.initials: R
authors.lastname: Gupta
authors.forename: Larisa P
authors.initials: LP
authors.lastname: Safonova
authors.forename: L Adelina
authors.initials: LA
authors.lastname: Paunescu
authors.forename: Antonios
authors.initials: A
authors.lastname: Michalos
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
mesh_terms: D004292:Dominance, Cerebral / Q000502:physiology; D005240:Feasibility Studies; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009044:Motor Cortex / Q000098:blood supply / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin