title: Does shape discrimination by the mouth activate the parietal and occipital lobes? - near-infrared spectroscopy study.
abstract: A cross-modal association between somatosensory tactile sensation and parietal and occipital activities during Braille reading was initially discovered in tests with blind subjects, with sighted and blindfolded healthy subjects used as controls. However, the neural background of oral stereognosis remains unclear. In the present study, we investigated whether the parietal and occipital cortices are activated during shape discrimination by the mouth using functional near-infrared spectroscopy (fNIRS). Following presentation of the test piece shape, a sham discrimination trial without the test pieces induced posterior parietal lobe (BA7), extrastriate cortex (BA18, BA19), and striate cortex (BA17) activation as compared with the rest session, while shape discrimination of the test pieces markedly activated those areas as compared with the rest session. Furthermore, shape discrimination of the test pieces specifically activated the posterior parietal cortex (precuneus/BA7), extrastriate cortex (BA18, 19), and striate cortex (BA17), as compared with sham sessions without a test piece. We concluded that oral tactile sensation is recognized through tactile/visual cross-modal substrates in the parietal and occipital cortices during shape discrimination by the mouth.
authors.affiliation: Gerodontology and Oral Rehabilitation Department of Gerontology and Gerodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kagawa
authors.affiliation: Department of Removable Prosthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Narita
authors.affiliation: Cognition and Action Research Group, Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Aist Tsukuba Central 6, Ibaraki, Japan.
authors.forename: Sunao
authors.initials: S
authors.lastname: Iwaki
authors.affiliation: Application Development Office, Hitachi Medical Corporation, Chiba, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kawasaki
authors.affiliation: Department of Removable Prosthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Kamiya
authors.affiliation: Gerodontology and Oral Rehabilitation Department of Gerontology and Gerodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Minakuchi
mesh_terms: D000328:Adult; D001766:Blindness / Q000503:physiopathology; D004192:Discrimination, Psychological / Q000502:physiology*; D006801:Humans; D008297:Male; D009055:Mouth / Q000503:physiopathology*; D009473:Neuronal Plasticity / Q000502:physiology; D009778:Occipital Lobe / Q000503:physiopathology*; D010296:Parietal Lobe / Q000503:physiopathology*; D011932:Reading; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D014110:Touch / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology