title: Laterality of human primary gustatory cortex studied by MEG.
abstract: We examined the laterality of the human gustatory neural pathway by measuring gustatory-evoked magnetic fields (GEMfs) and demonstrating the activation of the human primary gustatory cortex (PGC). In patients whose chorda tympani nerve had been severed unilaterally on the right side, we stimulated the normal side (i.e., left side) of the chorda tympani nerve with NaCl solution using a device developed for measuring GEMfs. We used the whole-head magnetoencephalography system for recording GEMfs and analyzed the frequency and latency of PGC activation in each hemisphere. "The transitional cortex between the insula and the parietal operculum" was identified as PGC with the base of the central sulcus in this experiment. Significant difference was found in frequencies among bilateral, only-ipsilateral, and only-contralateral responses by the Friedman test (P < 0.05), and more frequent bilateral responses were observed than only-ipsilateral (P < 0.05) or only-contralateral responses (P < 0.01) by the multiple comparison tests. In the bilateral responses, the averaged activation latencies of the transitional cortex between the insula and the parietal operculum were not significantly different in both hemispheres. These results suggest that unilateral gustatory stimulation will activate the transitional cortex between the insula and the parietal operculum bilaterally in humans.
authors.affiliation: Department of Otolaryngology, Nihon University School of Medicine, 30-1 Oyaguchi-kamicho, Itabashi-ku, Tokyo 173-8610, Japan. okeiko@med.nihon-u.ac.jp
authors.forename: Keiko
authors.initials: K
authors.lastname: Onoda
authors.forename: Tatsu
authors.initials: T
authors.lastname: Kobayakawa
authors.forename: Minoru
authors.initials: M
authors.lastname: Ikeda
authors.forename: Sachiko
authors.initials: S
authors.lastname: Saito
authors.forename: Akinori
authors.initials: A
authors.lastname: Kida
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D002814:Chorda Tympani Nerve / Q000293:injuries / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013003:Somatosensory Cortex / Q000502:physiology*; D013649:Taste / Q000502:physiology*; D013997:Time Factors
chemical_list: D012965:Sodium Chloride