Distinct Olfactory Cross-Modal Effects on the Human Motor System

BACKGROUND: Converging evidence indicates that action observation and action-related sounds activate cross-modally the human motor system. Since olfaction, the most ancestral sense, may have behavioural consequences on human activities, we causally investigated by transcranial magnetic stimulation (TMS) whether food odour could additionally facilitate the human motor system during the observation of grasping objects with alimentary valence, and the degree of specificity of these effects. METHODOLOGY/PRINCIPAL FINDINGS: In a repeated-measure block design, carried out on 24 healthy individuals participating to three different experiments, we show that sniffing alimentary odorants immediately increases the motor potentials evoked in hand muscles by TMS of the motor cortex. This effect was odorant-specific and was absent when subjects were presented with odorants including a potentially noxious trigeminal component. The smell-induced corticospinal facilitation of hand muscles during observation of grasping was an additive effect which superimposed to that induced by the mere observation of grasping actions for food or non-food objects. The odour-induced motor facilitation took place only in case of congruence between the sniffed odour and the observed grasped food, and specifically involved the muscle acting as prime mover for hand/fingers shaping in the observed action. CONCLUSIONS/SIGNIFICANCE: Complex olfactory cross-modal effects on the human corticospinal system are physiologically demonstrable. They are odorant-specific and, depending on the experimental context, muscle- and action-specific as well. This finding implies potential new diagnostic and rehabilitative applications

Not all flavor expertise is equal : The language of wine and coffee experts

People in Western cultures are poor at naming smells and flavors. However, for wine and coffee experts, describing smells and flavors is part of their daily routine. So are experts better than lay people at conveying smells and flavors in language? If smells and flavors are more easily linguistically expressed by experts, or more "codable", then experts should be better than novices at describing smells and flavors. If experts are indeed better, we can also ask how general this advantage is: do experts show higher codability only for smells and flavors they are expert in (i.e., wine experts for wine and coffee experts for coffee) or is their linguistic dexterity more general? To address these questions, wine experts, coffee experts, and novices were asked to describe the smell and flavor of wines, coffees, everyday odors, and basic tastes. The resulting descriptions were compared on a number of measures. We found expertise endows a modest advantage in smell and flavor naming. Wine experts showed more consistency in how they described wine smells and flavors than coffee experts, and novices; but coffee experts were not more consistent for coffee descriptions. Neither expert group was any more accurate at identifying everyday smells or tastes. Interestingly, both wine and coffee experts tended to use more source-based terms (e.g., vanilla) in descriptions of their own area of expertise whereas novices tended to use more evaluative terms (e.g., nice). However, the overall linguistic strategies for both groups were en par. To conclude, experts only have a limited, domain-specific advantage when communicating about smells and flavors. The ability to communicate about smells and flavors is a matter not only of perceptual training, but specific linguistic training too

Thought for food: Cognitive influences on chemosensory perceptions and preferences.

Sensory and consumer research often focuses more on bottom-up than top-down influences on consumers\u2019 perception and acceptance of foods. Yet, cognitive processes create and transform incoming sensory information originating from separate senses, including olfaction, gustation, and somatosensation, into the perception of flavour. The present paper discusses five cognitive processes that affect human chemosensory perception and responses to food flavours: Attention, language, memory, learning, and metacognition. It is argued that each of these processes are important in shaping interactions with food via the chemical senses. Attention moderates perception through its distribution across the environment, fine-tuning it for particular stimuli. Interactions among smells, tastes, and textures are acquired through learning, as are hedonic properties. Language affects food acceptability and preference, as does the memory of prior experiences with a food, even when they are not at a conscious level of processing. Metacognitive knowledge of personal capabilities indirectly influences the results of sensory evaluations. Future sensory and consumer research should take into account the significant role that these cognitive factors play in processing incoming chemosensory information