title: Application of near-infrared spectroscopy to measurement of hemodynamic signals accompanying stimulated saliva secretion.
abstract: We aim to test the feasibility of using near-infrared spectroscopy (NIRS) for indirect measurement of human saliva secretion in response to taste stimuli for potential application to organoleptic testing. We use an NIRS system to measure extracranial hemodynamics (Hb-signals around the temples) of healthy participants when taste stimuli are taken in their mouths. First, the Hb-signals and volume of expelled saliva (stimulated by distilled-water or sucrose-solution intake) are simultaneously measured and large Hb-signal changes in response to the taste stimuli (Hb-responses) are found. Statistical analysis show that both the Hb response and saliva volume are larger for the sucrose solution than for the distilled water with a significant correlation between them (r = 0.81). The effects of swallowing on the Hb-signals are investigated. Similar Hb responses, differing from the sucrose solution and distilled water, are obtained even though the participants swallow the mouth contents. Finally, functional magnetic resonance imaging is used to identify possible sources of the Hb signals corresponding to salivation. Statistical analysis indicates similar responses in the extracranial regions, mainly around the middle meningeal artery. In conclusion, the identified correlation between extracranial hemodynamics and the saliva volume suggests that NIRS is applicable to the measurement of hemodynamic signals accompanying stimulated saliva secretion.
authors.affiliation: Hitachi, Ltd, Advanced Research Laboratory, 2520 Akanuma, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sato
authors.forename: Akiko N
authors.initials: AN
authors.lastname: Obata
authors.forename: Ichiro
authors.initials: I
authors.lastname: Moda
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Ozaki
authors.forename: Takaomi
authors.initials: T
authors.lastname: Yasuhara
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Masashi
authors.initials: M
authors.lastname: Kiguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Maki
authors.forename: Kisou
authors.initials: K
authors.lastname: Kubota
authors.forename: Hideaki
authors.initials: H
authors.lastname: Koizumi
mesh_terms: D000328:Adult; D005260:Female; D005546:Forehead / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012463:Saliva / Q000378:metabolism; D012472:Salivation / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D018709:Statistics, Nonparametric; D013395:Sucrose; D013649:Taste / Q000502:physiology*; D014867:Water
chemical_list: D006454:Hemoglobins; D014867:Water; D013395:Sucrose