title: Localization of brain activation by umami taste in humans.
abstract: There are no credible data to support the notion that individual taste qualities have dedicated pathways leading from the tongue to the end of the pathway in the brain. Moreover, the insular cortex is activated not only by taste but also by non-taste information from oral stimuli. These responses are invariably excitatory, and it is difficult to determine whether they are sensory, motor, or proprioceptive in origin. Furthermore, umami is a more unfamiliar and complex taste than other basic tastes. Considering these issues, it may be effective to minimize somatosensory stimuli, oral movement, and psychological effects in a neuroimaging study to elicit cerebral activity by pure umami on the human tongue. For this purpose, we developed an original taste delivery system for functional magnetic resonance imaging (fMRI) studies for umami. Then, we compared the results produced by two authorized models, namely, the block design model and event-related design model, to decide the appropriate model for detecting activation by umami. Activation by the umami taste was well localized in the insular cortex using our new system and block design model analysis. The peaks of the activated areas in the middle insular cortex by umami were very close to another prototypical taste quality (salty). Although we have to carefully interpret the perceiving intensities and brain activations by taste from different sessions, this study design might be effective for detecting the accession area in the cortex of pure umami taste on the tongue.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Japan. nakamura@rad.dent.kyushu-u.ac.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Tazuko K
authors.initials: TK
authors.lastname: Goto
authors.forename: Kenji
authors.initials: K
authors.lastname: Tokumori
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshiura
authors.forename: Koji
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Ninomiya
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yoshiura
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007291:Inosine Monophosphate / Q000008:administration & dosage; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000098:blood supply; D010100:Oxygen / Q000097:blood; D015203:Reproducibility of Results; D012970:Sodium Glutamate / Q000008:administration & dosage; D013268:Stimulation, Chemical; D013649:Taste / Q000502:physiology*; D013652:Taste Threshold / Q000502:physiology; D055815:Young Adult
chemical_list: D007291:Inosine Monophosphate; D010100:Oxygen; D012970:Sodium Glutamate