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

PLoS One. 2017 Dec 27;12(12):e0190164. doi: 10.1371/journal.pone.0190164. eCollection 2017.

Abstract

Background: 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).

Design: 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.

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain Mapping
  • Cerebral Cortex / diagnostic imaging
  • Cerebral Cortex / physiology*
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Pilot Projects
  • Taste*
  • Young Adult

Grant support

The study was supported in part by The Beverage Institute for Health & Wellness, The Coca Cola Company, L.L.C., Atlanta, USA and the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.