Cerebral bases of emotion regulation toward odours: A first approach

• Regulation of odour-induced emotions results in higher activation of the dorsolateral prefrontal cortex and the anterior insula.
• Regulation of odour-induced emotions results in mild lower activation of the amygdala.
• Orbitofrontal cortex is less activated during regulation compared to maintain emotions.
• Regulation of positive odour-induced emotions results in activation of the supplementary motor area.
• Regulation of negative odour-induced emotions results in activation of the posterior cingulate gyrus.

Emotion regulation is defined as an important mechanism for human adaptation. fMRI studies have recently highlighted its neural bases but most research uses visual stimulation to induce emotion, none of them using odorant stimulations. Nevertheless, olfaction is intimately linked to emotional processes, sharing some same neural bases and thus constitutes a valuable emotion-inducer in experimental conditions. The present study aims to determine the cerebral areas which might be involved in down-regulation, using pleasant and unpleasant odours as emotion-inducers. Eighteen subjects were scanned during 2 sequences of 12 stimulations, each with either a pleasant or an unpleasant odour. For one sequence, subjects were instructed to naturally experience their emotion induced by odour inhalation and for the other one, to decrease the intensity of their emotion. Consistent with previous work using emotion-inducers, emotion regulation resulted in higher activations of the dorsolateral prefrontal cortex and the anterior insula, but in lower activation of the amygdala. However, some areas (the posterior cerebellum and the orbitofrontal cortex) are less activated during regulation compared to maintain and thus appear to be specific to odorant stimulations. Finally the hedonic valence of the odour determines activations in different brain areas such as the supplementary motor area and the posterior cingulum. Thus, this study suggests abilities to regulate emotion in response to odours, involving brain areas usually described in the literature for other emotional stimuli, but also specific areas depending partly of the hedonic valence of the odour.