Cortical representation of different taste modalities on the gustatory cortex: A pilot study

• Published in: PloS one Vol. 12; no. 12; p. e0190164
• Main Authors: Prinster, Anna, Cantone, Elena, Verlezza, Viviana, Magliulo, Mario, Sarnelli, Giovanni, Iengo, Maurizio, Cuomo, Rosario, Di Salle, Francesco, Esposito, Fabrizio
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 27.12.2017; Public Library of Science (PLoS)
• Subjects: Auditory discrimination; Biology; Biology and Life Sciences; Bitter taste; Brain research; Carbon dioxide; Carbonates; Carbonation; Chlorine compounds; Citric acid; Cortex (auditory); Cortex (gustatory); Cortex (insular); Cortex (somatosensory); Dentistry; Earth Sciences; Ecology and Environmental Sciences; Functional magnetic resonance imaging; Functional morphology; Gastroenterology; Head movement; Image resolution; Localization; Magnetic resonance; Magnetic resonance imaging; Medicine; Medicine and Health Sciences; Neuroimaging; Neurosciences; Nutrients; Perception (Psychology); Phosphates; Physical properties; Physical Sciences; Physiology; Potassium; Psychological aspects; Quality; Representations; Research and Analysis Methods; Salts; Sensory integration; Social Sciences; Sodium; Sodium chloride; Somatosensory cortex; Statistical analysis; Sweet taste; Taste; Taste (Sense); Taste discrimination; Umami; Visual cortex; Visual discrimination
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0190164

Right insular cortex is involved in taste discrimination, but its functional organization is still poorly known. In general, sensory cortices represent the spatial prevalence of relevant features for each sensory modality (visual, auditory, somatosensory) in an ordered way across the cortical space. Following this analogy, we hypothesized that primary taste cortex is organized in similar ordered way in response to six tastes with known receptorial mechanisms (sweet, bitter, sour, salt, umami, CO2). Ten normal subjects were enrolled in a pilot study. We used functional magnetic resonance imaging (fMRI), a high resolution cortical registration method, and specialized procedures of feature prevalence localization, to map fMRI responses within the right insular cortex, to water solutions of quinine hydrochloride (bitter), Acesulfamate K (sweet), sodium chloride (salt), mono potassium glutamate + inosine 5' mono phosphate (Umami), citric acid (sour) and carbonated water (CO2). During an fMRI scan delivery of the solutions was applied in pseudo-random order interleaved with cleaning water. Two subjects were discarded due to excessive head movements. In the remaining subjects, statistically significant activations were detected in the fMRI responses to all tastes in the right insular cortex (p<0.05, family-wise corrected for multiple comparisons). Cortical representation of taste prevalence highlighted two spatially segregated clusters, processing two and three tastes coupled together (sweet-bitter and salt-umami-sour), with CO2 in between. Cortical representation of taste prevalence within the right primary taste cortex appears to follow the ecological purpose of enhancing the discrimination between safe nutrients and harmful substances.