title: Functional MRI cortical activations from unilateral tactile-taste stimulations of the tongue.
abstract: Functional magnetic resonance imaging (fMRI) was used for revealing activations in the human brain by lateralized tactile-gustatory stimulations of the tongue. Salt, a basic taste stimulus, and water, now recognized as an independent taste modality, were applied to either hemitongues with pads similar to the taste strips test for the clinical psychophysical evaluation of taste. With both stimuli, the observed cortical patterns of activations could be attributed to a combined somatosensory and gustatory stimulation of the tongue, with no significant differences between salt and water. Stimulation of each hemitongue evoked a bilateral activation of the anterior insula-frontal operculum, ascribable to the gustatory component of the stimulation, and a bilateral activation of the inferior part of the postcentral gyrus, ascribable to the tactile component of the stimulation. The results are in line with the notion that the representation of the tongue in the cerebral hemispheres in both the touch and the taste modalities is bilateral. Clinical and brain stimulation findings indicate that this bilaterality depends primarily on a partial crossing of the afferent pathways, perhaps with a predominance of the crossed pathway in the touch modality and the uncrossed pathway in the taste modality. Previous evidence suggests that the corpus callosum is not indispensible for this bilateral representation, but can contribute to it by interhemispheric transfer of information in both modalities.
authors.affiliation: Dipartimento di Scienze Cliniche e Odontostomatologiche, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Mascioli
authors.affiliation: Dipartimento di Scienze Neurologiche e del Movimento, Università degli Studi di Verona, Italy; National Institute of Neuroscience, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Berlucchi
authors.affiliation: Dipartmento di Medicina Sperimentale e Clinica, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Pierpaoli
authors.affiliation: Dipartimento di Scienze Cliniche e Odontostomatologiche, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Ugo
authors.initials: U
authors.lastname: Salvolini
authors.affiliation: Dipartmento di Medicina Sperimentale e Clinica, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Barbaresi
authors.affiliation: Dipartmento di Medicina Sperimentale e Clinica, Università Politecnica delle Marche, Ancona, Italy. Electronic address: m.fabri@univpm.it.
authors.forename: Mara
authors.initials: M
authors.lastname: Fabri
authors.affiliation: Dipartimento di Scienze Cliniche e Odontostomatologiche, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Polonara
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D060766:Drinking Water / Q000008:administration & dosage; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010812:Physical Stimulation; D012982:Sodium, Dietary / Q000008:administration & dosage; D055697:Taste Perception / Q000502:physiology*; D014059:Tongue / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
chemical_list: D060766:Drinking Water; D012982:Sodium, Dietary
keywords: Bilateral activation; Corpus callosum; Gustatory stimulation; Tongue representation; fMRI