046-22 – The Impact Of Skin Hydration & Dehydration On Nerve Responses To Dynamic Touch Is More Than Skin Deep

Skin has two primary functions of equal importance: 1. as a selectively permeable barrier responsible for osmoregulation, and 2. as the largest sensory organ. Both these functions are interdependent.

Several studies have considered the impact of skin hydration / moisturisers on tactile perception on glabrous skin – however little is known about the effect on hairy skin, or in unmyelinated nerve fibres, and effects of dehydration are underexplored – particularly significant since the start of the coronavirus pandemic.

This study aimed to address these gaps using two different approaches:
1. An electrophysiological study of cutaneous afferent activity in hairy skin, pre- and post- hydration / dehydration using microneurography.
2. A psychophysiological study investigating the subjective / perceptual impact of hydration / dehydration in response to gentle stroking touch applied to the forearm.

Results show acute hydration of the skin with moisturising cream enhanced pleasantness ratings for typically pleasant dynamic stimuli i.e. soft, slow brushing, and had a mediating effect on typically unpleasant stimuli, i.e. rough, fast brushing. The perceptual ratings correspond to relatively lower firing of both Aβ (Fast Adapting) Field and Aβ Slow Adapting (SA) II Afferents, whereas firing of Aβ Hair, and C-Tactile afferents is enhanced post-treatment with cream – which also suggests effective hydration of the skin may enhance the pleasantness of social and affective touch.