Changes in tactile spatial discrimination and cutaneous coding properties by skin hydration in the elderly

Area of Science:

• Neuroscience
• Dermatology
• Human Physiology

Background:

• Aging significantly degrades neurosensory tactile functions, specifically spatial acuity.
• The stratum corneum's properties influence tactile perception and discrimination.
• Hydration is explored as a potential method to restore tactile functions.

Purpose of the Study:

• To investigate the impact of skin hydration on tactile spatial acuity in humans.
• To elucidate the mechanisms underlying changes in tactile function following skin hydration.
• To compare psychophysical and microneurographic approaches in assessing tactile responses.

Main Methods:

• Conventional psychophysical method: two-point gap discrimination to assess tactile spatial acuity.
• Microneurographic recording of tactile afferent fibers in response to mechanical stimuli.
• Application of moisturizers to investigate the effect of skin hydration.

Main Results:

• Tactile spatial acuity significantly degrades with age.
• Skin hydration partially restored tactile discriminative function.
• Microneurographic recordings showed depressed afferent messages after hydration.
• Hydration softens the stratum corneum, improving stimulus localization and reducing signal transfer to receptors.

Conclusions:

• Skin hydration effectively restores tactile spatial acuity, particularly in aged individuals.
• The restoration of tactile function is attributed to altered mechanical properties of the stratum corneum and modified afferent nerve activity.
• Combining psychophysical and microneurographic methods provides a comprehensive understanding of tactile sensory mechanisms.