Olfactory Network Differences in Master Sommeliers: Connectivity Analysis Using Granger Causality and Graph Theoretical Approach

Abstract

Previous studies investigating the differences in olfactory processing and judgments between trained sommeliers and controls have shown increased activations in brain regions involving higher level cognitive processes in sommeliers. However, there is little information about the influence of expertise on causal connectivity and topological properties of the connectivity networks between these regions. Therefore, the current study focuses on addressing these questions in a functional magnetic resonance imaging (fMRI) study of olfactory perception in Master Sommeliers. fMRI data were acquired from Master Sommeliers and control participants during different olfactory and nonolfactory tasks. Mean time series were extracted from 90 different regions of interest (ROIs; based on Automated Anatomical Labeling atlas). The underlying neuronal variables were extracted using blind hemodynamic deconvolution and then input into a dynamic multivariate autoregressive model to obtain connectivity between every pair of ROIs as a function of time. These connectivity values were then statistically compared to obtain paths that were significantly different between the two groups. The obtained connectivity matrices were further studied using graph theoretical methods. In sommeliers, significantly greater connectivity was observed in connections involving the precuneus, caudate, putamen, and several frontal and temporal regions. The controls showed increased connectivity from the left hippocampus to the frontal regions. Furthermore, the sommeliers exhibited significantly higher small-world topology than the controls. These findings are significant, given that learning about neuroplasticity in adulthood in these regions may then have added clinical importance in diseases such as Alzheimer's and Parkinson's where early neurodegeneration is isolated to regions important in smell.

The Effect of Media Professionalization on Cognitive Neurodynamics During Audiovisual Cuts

“…We found that the connectivity originating in those three areas (corresponding with visual cortex, somatomotor area, and frontal area) was stronger in media professionals. This is coincident with previous studies that attributed stronger connectivity in professionals compared with control groups to the learning undertaken because of their expertise (Sreenivasan et al, 2017 ), and that suggested an increased neural efficiency in the brain of highly skilled individuals (Bernardi et al, 2013 ). The fact that that higher connectivity in media professionals occurs in visual cortex could be related to the importance of that area for visual processing in their daily work.…”

Occupational Neuroplasticity in the Human Brain: A Critical Review and Meta-Analysis of Neuroimaging Studies

“…Interestingly, studies (Kawabata and Zeki, 2004 ; Vartanian and Goel, 2004 ) have shown that expertise influences aesthetic judgments, and architects with aesthetic expertise (Kirk et al, 2009 ) showed differential activation of the bilateral subcallosal cingulate gyrus and medial orbitofrontal cortex compared to non-architects during this judgment. Furthermore, sommeliers (wine experts) (Pazart et al, 2014 ) also showed activation in the temporal pole and hippocampal and parahippocampal formations when tasting wine; Sreenivasan et al ( 2017 ) have explored the influence of expertise on causal connectivity and topological property related to master sommeliers during different olfactory and non-olfactory tasks, where in sommeliers, a significantly greater connectivity involving the precuneus, caudate, putamen, and several frontal and temporal regions was observed and a significantly higher small-world topology was identified.…”

Characterizing functional pathways of the human olfactory system

“…Previous studies have used task-related and resting functional magnetic resonance imaging (fMRI) to examine olfactory networks, using primary olfactory and orbitofrontal cortices as seed regions (Banks et al, 2016; Cecchetto et al, 2019; Fjaeldstad et al, 2017; Karunanayaka et al, 2017; Karunanayaka et al, 2014; Kiparizoska and Ikuta, 2017; Kollndorfer et al, 2015; Krusemark and Li, 2012; Nigri et al, 2013; Sreenivasan et al, 2017; Sunwoo et al, 2015). These studies have contributed important broad knowledge of parallel olfactory networks (Karunanayaka et al, 2014), how they compare to trigeminal networks (Karunanayaka et al, 2017), and how they change with age (Wang et al, 2005) and disease (Caffo et al, 2010; Fjaeldstad et al, 2017; Killgore et al, 2013; Sunwoo et al, 2015; Wang et al, 2010; Wang et al, 2015).…”