title: Changes of evoked cerebral blood oxygenation and optical pathlength in the frontal lobe during language tasks: a study by multi-channel, time-resolved near-infrared spectroscopy and functional MRI.
abstract: To determine the alterations in optical characteristics and cerebral blood oxygenation (CBO) in the frontal lobe during language tasks, we evaluated the changes in mean optical pathlength (MOP) and CBO induced by a verbal fluency task (VFT) in the right and left frontal lobes in normal adults (n = 9, mean age = 29.6 +/- 4.8 years). We employed a newly developed 8-channel time-resolved near-infrared spectroscopy (TRS) instrument. The results demonstrated differences in MOP in the fronto-temporal areas with subject and wavelength; however, there was no significant difference between the right and left sides (p > 0.05). Also, the VFT did not affect the MOP significantly as compared to that before the tasks (p > 0.05). In all of the recording regions, the VFT caused increases in concentration of oxyhemoglobin and total hemoglobin associated with a decrease in deoxyhemoglobin concentration, indicating that these cortical areas were activated by the VFT. However, the mean concentration changes of oxyhemoglobin and total hemoglobin on the left side were larger than those on the right side. In addition, functional MRI demonstrated that the inferior frontal gyrus on the left side was activated in the subjects who exhibited increases in oxyhemoglobin concentration in these areas. These results suggest that TRS may be useful to study language function and to assess hemispheric dominance for language.
authors.affiliation: Division of Neurosurgery, Department of Neurological Surgery, Nihon University School of Medicine, Tokyo, Japan. ymcooper@med.nihon-u.ac.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Murata
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sakatani
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hoshino
authors.forename: Norio
authors.initials: N
authors.lastname: Fujiwara
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Katayama
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamashita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Motoki
authors.initials: M
authors.lastname: Oda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D055620:Optical Phenomena; D010100:Oxygen / Q000097:blood*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013647:Task Performance and Analysis; D013997:Time Factors
chemical_list: D006454:Hemoglobins; D010100:Oxygen