Neuromechanical representation of fabric-evoked prickliness: a fiber-skin-neuron model

Cutaneous Aδ nociceptors encode the material and geometrical features of fiber ends evoking prickliness sensation by generating neural spikes in response to indentation of human skin, however, understanding of the underlying neuromechanism of fabric-evoked prickliness is still far from clear. This work develops and validates a fiber-skin-neuron (mechanosensitive Aδ-nociceptors) model that combines an analytical model of fiber-skin indentation, a sigmoidal function of neuronal transduction, and a leaky integrate-and-fire model of neuronal dynamics. Firstly, the model is validated to be capable of capturing the typical neurphysiological features of cutaneous Aδ nociceptors and the psychophysical phenomenon. And then, several case studies with respect to statistical features of fiber ends are carried out, and the resulting neural responses are calculated to explore the relationship between statistical features in study and evoked responses. The analysis of predicted action potentials over one second indicates that they systematically change with statistical features of fiber ends protruding above fabric surfaces, and the fitted stimulus-response relationship of Aδ nociceptors is highly similar to the stimulus-sensation relationship of prickliness rating magnitude. It follows that there might exist a linear relationship between fabric-evoked neurophysiological responses and psychophysical responses. These results provide significant new insight into the fabric-evoked prickliness sensation and raise interesting questions for further investigation, and the model described here bridges the gap between those models that transform fiber ends properties to firing rates.