title: Thermal taster status: Evidence of cross-modal integration.
abstract: Thermal taster status refers to the finding that, in some individuals, thermal stimulation of the tongue elicits a phantom taste. Little is known regarding the mechanism for this, it is hypothesised to be a result of cross-wiring between gustatory and trigeminal nerves whose receptors co-innervate papillae on the tongue. To address this, we use functional magnetic resonance imaging to perform the first study of whether the cortical response to gustatory-trigeminal samples is altered with thermal taster status. We study the response to cold (6°C) gustatory (sweet) samples at varying levels of trigeminal stimulation elicited by CO2 (no CO2 , low CO2 , high CO2 ) in thermal taster (TT) and thermal non-taster (TnT) groups, and evaluate associated behavioural measures. Behaviourally, the TT group perceived gustatory and trigeminal stimuli significantly more intense than TnTs, and were significantly more discriminating of CO2 level. fMRI data revealed elevated cortical activation to the no CO2 sample for the TT group compared to TnT group in taste, oral somatosensory and reward areas. In TnTs, a significant positive modulation in cortical response with increasing level of CO2 was found across taste, somatosensory and reward areas. In contrast, in TTs, a reduced positive modulation with increasing level of CO2 was found in somatosensory areas (SI, SII), whilst a significant negative modulation was found in taste (anterior insula) and reward (ACC) areas. This difference in cortical response to trigeminal stimuli supports cross-modal integration in TTs, with gustatory and trigeminal nerves highly stimulated by cold gustatory samples due to their intertwined nature. Hum Brain Mapp 37:2263-2275, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Sensory Science Centre, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, United Kingdom.
authors.forename: Joanne
authors.initials: J
authors.lastname: Hort
authors.affiliation: Sensory Science Centre, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, United Kingdom.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Ford
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, United Kingdom.|Physics Department, Faculty of Science, Suez Canal University, Ismailia, Egypt.
authors.forename: Sally
authors.initials: S
authors.lastname: Eldeghaidy
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, United Kingdom.
authors.forename: Susan T
authors.initials: ST
authors.lastname: Francis
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010812:Physical Stimulation; D055697:Taste Perception / Q000502:physiology*; D013696:Temperature; D013697:Thermosensing / Q000502:physiology*; D014276:Trigeminal Nerve / Q000502:physiology
keywords: BOLD; fMRI; insula; oral somatosensory; taste; thermal taster status; trigeminal