title: Direct cortical hemodynamic mapping of somatotopy of pig nostril sensation by functional near-infrared cortical imaging (fNCI).
abstract: Functional near-infrared spectroscopy (fNIRS) is a neuroimaging technique for the noninvasive monitoring of human brain activation states utilizing the coupling between neural activity and regional cerebral hemodynamics. Illuminators and detectors, together constituting optodes, are placed on the scalp, but due to the presence of head tissues, an inter-optode distance of more than 2.5cm is necessary to detect cortical signals. Although direct cortical monitoring with fNIRS has been pursued, a high-resolution visualization of hemodynamic changes associated with sensory, motor and cognitive neural responses directly from the cortical surface has yet to be realized. To acquire robust information on the hemodynamics of the cortex, devoid of signal complications in transcranial measurement, we devised a functional near-infrared cortical imaging (fNCI) technique. Here we demonstrate the first direct functional measurement of temporal and spatial patterns of cortical hemodynamics using the fNCI technique. For fNCI, inter-optode distance was set at 5mm, and light leakage from illuminators was prevented by a special optode holder made of a light-shielding rubber sheet. fNCI successfully detected the somatotopy of pig nostril sensation, as assessed in comparison with concurrent and sequential somatosensory-evoked potential (SEP) measurements on the same stimulation sites. Accordingly, the fNCI system realized a direct cortical hemodynamic measurement with a spatial resolution comparable to that of SEP mapping on the rostral region of the pig brain. This study provides an important initial step toward realizing functional cortical hemodynamic monitoring during neurosurgery of human brains.
authors.affiliation: Center for Development of Advanced Medical Technology, Jichi Medical University, Tochigi 329-0498, Japan; Research and Development Initiatives/Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Uga
authors.affiliation: Center for Development of Advanced Medical Technology, Jichi Medical University, Tochigi 329-0498, Japan; Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Saito
authors.affiliation: Center for Development of Advanced Medical Technology, Jichi Medical University, Tochigi 329-0498, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Sano
authors.affiliation: Department of Neurosurgery, Jichi Medical University, Tochigi 329-0498, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yokota
authors.affiliation: Department of Neurosurgery, Jichi Medical University, Tochigi 329-0498, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Oguro
authors.affiliation: Department of Neurosurgery, Jichi Medical University, Tochigi 329-0498, Japan.
authors.forename: Edmi Edison
authors.initials: EE
authors.lastname: Rizki
authors.affiliation: Center for Development of Advanced Medical Technology, Jichi Medical University, Tochigi 329-0498, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Mizutani
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Hatoyama, Saitama 350-0395, Japan.
authors.forename: Takusige
authors.initials: T
authors.lastname: Katura
authors.affiliation: Center for Development of Advanced Medical Technology, Jichi Medical University, Tochigi 329-0498, Japan; Research and Development Initiatives/Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan. Electronic address: dan@jichi.ac.jp.
authors.forename: Ippeita
authors.initials: I
authors.lastname: Dan
authors.affiliation: Center for Development of Advanced Medical Technology, Jichi Medical University, Tochigi 329-0498, Japan; Department of Neurosurgery, Jichi Medical University, Tochigi 329-0498, Japan.
authors.forename: Eiju
authors.initials: E
authors.lastname: Watanabe
mesh_terms: D000465:Algorithms; D000818:Animals; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000098:blood supply* / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D008297:Male; D009296:Nasal Cavity / Q000033:anatomy & histology* / Q000502:physiology; D059906:Neuroimaging / Q000379:methods*; D010108:Oxyhemoglobins / Q000378:metabolism; D013003:Somatosensory Cortex / Q000502:physiology; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013552:Swine
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin
keywords: Brain mapping; Cortical representation; Electrocorticogram; Miniature pig; Optical topography