Mechanisms of tactile sensory deterioration amongst the elderly

Lisa Skedung,Gustavo S Luengo,Charles El Rawadi,Lionel Breton,Céline Farcet,Mark W Rutland,Martin Arvidsson

doi:10.1038/s41598-018-23688-6

Lisa Skedung, Gustavo S Luengo + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-23688-6

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Abstract

It is known that roughness-smoothness, hardness-softness, stickiness-slipperiness and warm-cold are predominant perceptual dimensions in macro-, micro- and nano- texture perception. However, it is not clear to what extent active tactile texture discrimination remains intact with age. The general decrease in tactile ability induces physical and emotional dysfunction in elderly, and has increasing significance for an aging population. We report a method to quantify tactile acuity based on blinded active exploration of systematically varying micro-textured surfaces and a same-different paradigm. It reveals that elderly participants show significantly reduced fine texture discrimination ability. The elderly group also displays statistically lower finger friction coefficient, moisture and elasticity, suggesting a link. However, a subpopulation of the elderly retains discrimination ability irrespective of cutaneous condition and this can be related to a higher density of somatosensory receptors on the finger pads. Skin tribology is thus not the primary reason for decline of tactile discrimination with age. The remediation of cutaneous properties through rehydration, however leads to a significantly improved tactile acuity. This indicates unambiguously that neurological tactile loss can be temporarily compensated by restoring the cutaneous contact mechanics. Such mechanical restoration of tactile ability has the potential to increase the quality of life in elderly.

Highlights

In common only with taste, touch is based on the intimate contact of a body surface with a material and as with all senses, tactile perceptual ability declines with age[1,2,3,4]
The reduction in acuity amongst the elderly is matched by a reduction in the biomechanical properties of the skin – moisture, elasticity and finger friction coefficient are all significantly reduced
The finger friction is known as an important perceptual identifier for fine texture discrimination so this provides a clear pathway for amelioration of the reduced tactile perception

Summary

Introduction

In common only with taste, touch is based on the intimate contact of a body surface with a material and as with all senses, tactile perceptual ability declines with age[1,2,3,4]. There is an increased interest recently on methods based on stimuli detection; such psycho-physical techniques provide a complementary approach and rely on objective tests, such as whether a difference can be detected[14]. It is known that roughness-smoothness, hardness-softness and stickiness-slipperiness are predominant perceptual (as opposed to physical) dimensions in macro texture perception[14,16,17,18]. This perceptual dimensionality remains intact when the texture scale is reduced to the micro- and nanoscale[19]. The questions can be posed as to whether i) there is a similar reduction in tactile sensory discrimination of fine texture with increasing age, ii) this deterioration can be attributed to age related changes in skin mechanical properties and iii) such mechanical deficiencies can be analogously remediated

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