Chemical senses and Consumer Technologies: a journey from the human physiology towards the Metaverse

Smell is one of the five human senses and it is intimately concerned with memory and emotions, given its peculiar anatomy and physiology. Once neglected by most of the scientific community, it is now re-discovered for its role as an early biomarker for cognitive impairment and for the useful information it provides about psychophysiological and emotional processes of the human body. Several methods have been developed for monitoring its functioning, many of which rely on questionnaires, made up of extrinsical variables, in turn somewhat affected by subjective biases. However, thanks to the technology spread into the scientific community and citizenship at large, it is nowadays possible, and viable, to monitor the intrinsical responses produced by olfactory stimuli into the human body. Such process ensures the extrapolation of objective data, less affected by conscious, subjective biases. To this extent, the application of wearables allow, for example, estimating the cardiac rhythm changes, or the modifications in the sweat glands activity during and after a stimulation, or the activation of different brain areas, matching the modifications occurring at the Central- and Autonomic Nervous System levels, providing an objective and precise estimation of processes occurring at the brain and body levels. This has manifold consequences, in several fields, including the estimation of the attentional levels in a given task (e.g., during studying, gaming, driving, etc.), and could potentially act as a therapeutic driver in selected clinical cases, including those with eating, neurodevelopmental or neurodegenerative disorders.