A new study* by researchers from Stanford University in the USA aims to quantify the mechanism whereby cutaneous mechanoreceptors and corresponding sensory neurons are activated during the neural signalling of skin sensory perception from topical treatments.
As the study notes, there is a sensation of skin ‘tightness’ after using a cleanser or ‘softness’ after applying a moisturizer. However, the mechanism whereby cutaneous mechanoreceptors and corresponding sensory neurons are activated giving rise to these perceptions had not previously been established. This new study provides a quantitative approach that couples in vitro biomechanical testing and detailed computational neural stimulation modelling along with a comprehensive in vivo self-assessment survey to demonstrate how cutaneous biomechanical changes in response to treatments are involved in the sensorial perception of the human skin. Strong correlations are identified between reported perception up to 12 hours post treatment and changes in the computed neural stimulation from mechanoreceptors residing deep under the skin surface.
The study reveals a quantitative framework for understanding the biomechanical neural activation mechanism and the subjective perception by individuals. In the study, a quantitative biomechanical mechanism is described whereby cutaneous mechanoreceptors and corresponding sensory neurons are distinctly activated in response to an array of topical skin treatments. The resulting neural signalling is used to explain the skin sensory perception subjectively reported by the perception assessment participants in a comprehensive study involving over 2,000 women in different countries over a 3-year period.
States the study: “A FE model of human skin from three anatomical sites was used to compute detailed strain distributions in full-thickness human skin. In addition, a separate FE model was developed for predicting SAI afferent firing rates based on strain induced from indentation contact in primate fingertips. It was subsequently used to predict mean firing rates among SAI afferent neurons in full-thickness skin at the three anatomical sites in response to SC stresses that developed from several topical skin treatments.
“Strong correlations are observed between skin sensory perception survey scores and the computed SAI neuron firing rates in full-thickness skin, implying that SAI neurons contribute to the perception of biomechanical changes of skin, such as skin tightness. The combination of experimental measurements and computational modelling presented in this study elucidates the biomechanical mechanism by which skin sensorial perception arises from the activation of cutaneous SAI neurons following the use of topical skin treatments.”
An ethical statement published at the end of the study reads: “The human skin sensorial perception assessment was a blind use test, monadic simple quantitative test, with a geographic repartition representative of the total population. The consumers were involved in the study after giving their informed consent. The protocol complied with the Helsinki declaration as revised in 2013. No ethical approval was required.”
To see the study click here
* ‘Sensory neuron activation from topical treatments modulates the sensorial perception of human skin.’ Ross Bennett-Kennett, Joseph Pace, Barbara Lynch, Yegor Domanov, Gustavo S Luengo, Anne Potter, Reinhold H Dauskardt
PNAS Nexus, Volume 2, Issue 9, September 2023, pgad292, https://doi.org/10.1093/pnasnexus/pgad292