Abstract
BackgroundDespite the growing number of discoveries during the past decades about its functions, the insula remains a mysterious ‘island’. In addition to its involvement in basic functions such as gustation and interoception, the insular cortex is now considered a key region for integrated functions such as emotion/motivation processing, decision-making and self-consciousness. We hypothesized that this structure, standing at the crossroads of such functions, could ground personal tastes in general, beyond food preferences and aesthetic judgements. Given that dementia with Lewy bodies is characterized by a focal atrophy within the insular cortex from the early stages, this condition provides an opportunity to test such a hypothesis.MethodsWe developed a questionnaire to assess potential changes in personal tastes, submitted it to a cohort of 23 patients with early-stage dementia with Lewy bodies and compared their questionnaire results to those of 20 age-matched healthy controls. Furthermore, we performed a global and regional neuroimaging study to test for a potential correlation between the patients’ scores for changes in personal tastes and their insular cortex volumes.ResultsOur results indicate that the patients presented significant changes in personal tastes compared to the controls, in both food and non-food domains. Moreover, imaging analyses confirmed the involvement of the insular cortex atrophy in the changes in personal tastes using global analysis, and in both food and non-food domains using regional analysis.ConclusionsThese results bring new insights into the role of the insula as a ‘grey matter of tastes’, this structure supporting personal preferences in general, beyond the food domain. The insular cortex could be involved through its role in motivational processes by the representation of subjective awareness of bodily states during the phenomenological experience of stimulus appraisal. However, we also argue that it could support the abstract representations of personal tastes as self-concepts, acutely exemplifying embodied cognition. Finally, the questionnaire on changes in tastes could constitute an interesting tool to help early diagnosis of dementia with Lewy bodies and to assess insular dysfunction more generally.
Highlights
Despite the growing number of discoveries during the past decades about its functions, the insula remains a mysterious ‘island’
Across literature [18,19,20,21,22], personal tastes are associated to some consistent characteristics, which could rely on the insular cortex, namely, subjectivity, pleasure/motivation and judgement/decision-making. (i) First, as conveyed by the expression ‘a matter of taste’, personal preferences are characterized by an idiosyncratic subjectivity
Our results bring new insights regarding the role of insular cortex in personal tastes in general, beyond food preference and aesthetic judgement, since we found insular cortex atrophy to be associated with changes in personal tastes, for food and non-food domains
Summary
Despite the growing number of discoveries during the past decades about its functions, the insula remains a mysterious ‘island’. In addition to its involvement in basic functions such as gustation and interoception, the insular cortex is considered a key region for integrated functions such as emotion/motivation processing, decision-making and self-consciousness. We hypothesized that this structure, standing at the crossroads of such functions, could ground personal tastes in general, beyond food preferences and aesthetic judgements. Standing at the crossroads of selfconsciousness, emotional/motivational and decisionmaking networks [1], the insular cortex appears as a potential key region to underpin personal tastes in general, likely co-opting the ancestral circuitry of food appraisal in the course of human evolutionary development [16]. Other potential anatomical supports of personal tastes are the cortical midline structures, such as the medial prefrontal and medial parietal cortices, which are key regions for self-processing in general and conceptual self in particular [26,27,28,29]
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