A common neural code for gustatory and olfactory stimuli in the human insular cortex
Poster No:
2011
Submission Type:
Abstract Submission
Authors:
Putu Khorisantono1, Maria Veldhuizen2, Janina Seubert3
Institutions:
1Karolinska Institutet, Stockholm, Stockholms län, 2Mersin University, Mersin, Mersin, 3Karolinska Institutet, Stockholm, Sweden
First Author:
Co-Author(s):
Introduction:
During food consumption, tastes combine with retronasal odours to form flavour, which leads to a link so robust that retronasal odours can elicit taste sensations without concurrent taste stimulation (Rozin, 1982). Despite the established association between odour and taste, the precise mechanism underlying this phenomenon remains elusive. Here, we build on prior research on distributed pattern encoding of tastants in the insula and frontal operculum (Avery et al., 2020; Chikazoe et al., 2019), along with activations in these structures in response to odours, to investigate the role of odours in flavour processing. Specifically, we combine a flavour-binding paradigm and functional neuroimaging to test whether retronasal odorants evoke encoding patterns in the insula similar to those of their paired tastants.
Methods:
In our pre-registered study, male and female healthy participants (N=25) attended a behavoural familiarisation session with with a congruent sweet flavour (a sweet taste with a sweet odour) and a congruent savoury flavour (a savoury taste with a savoury odour), followed by two fMRI sessions where they separately received the constituent tastants and odorants (Fig 1).
·Fig 1. Setup of the experiment. SweT: sweet taste; SweO: ‘sweet’ odour; SavT: savoury taste; SavO: ‘savoury’ odour; ArtS: artificial saliva
Results:
Univariate analyses replicated previous findings, showing activation in the insula in response to tastants and the piriform cortex in response to retronasal odours (Fig 2; de Araujo et al., 2003; Small & Prescott, 2005). Multivariate pattern analysis revealed classification of retronasal odours within the insula, exhibiting overlapping representations with their associated tastes. Crucially, after parcellating the insula based on layer morphology (granularity), this crossmodal overlap was observed only in the dysgranular and agranular insula. Additional analyses exploring temporal fluctuations in taste and flavour representations revealed instability in taste identity patterns, marking, to the best of our knowledge, the first formal investigation of gustatory representational drift in humans.
·Fig 2. Modality-specific univariate responses and ROI decoding.
Conclusions:
Taken together, our study highlights the role of the insula as a key hub for flavour integration via taste-odour convergence. These findings provide a neural basis for behavioural phenomena such as 'phantom tastes' and odour-induced taste enhancement. This process, likely mediated by reciprocal projections between the insula and piriform cortex, enables food odours to acquire taste attributes and hedonic value.These results emphasise the strong integration of gustatory and retronasal olfactory processing that forms the foundation of the flavour experience.
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Classification and Predictive Modeling 2
Multivariate Approaches
Novel Imaging Acquisition Methods:
BOLD fMRI
Perception, Attention and Motor Behavior:
Chemical Senses: Olfaction, Taste 1
Keywords:
Cortical Layers
FUNCTIONAL MRI
Multivariate
Pre-registration
Smell
Taste
Tongue
Other - flavour
1|2Indicates the priority used for review
Abstract Information
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Provide references using APA citation style.
Chikazoe, J., Lee, D. H., Kriegeskorte, N., & Anderson, A. K. (2019). Distinct representations of basic taste qualities in human gustatory cortex. Nature Communications, 10(1), 1–8. https://doi.org/10.1038/s41467-019-08857-z
de Araujo, I. E. T., Rolls, E. T., Kringelbach, M. L., McGlone, F., & Phillips, N. (2003). Taste-olfactory convergence, and the representation of the pleasantness of flavour, in the human brain. European Journal of Neuroscience, 18(7), 2059–2068. https://doi.org/10.1046/j.1460-9568.2003.02915.x
Rozin, P. (1982). ‘Taste-smell confusions’ and the duality of the olfactory sense. Perception & Psychophysics, 31(4), 397–401. https://doi.org/10.3758/BF03202667
Small, D. M., & Prescott, J. (2005). Odor/taste integration and the perception of flavor. Experimental Brain Research, 166(3–4), 345–357. https://doi.org/10.1007/s00221-005-2376-9