Cutaneous Sensitivity Across Regions of the Foot Sole and Dorsum are Influenced by Foot Posture (original) (raw)
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Physiological reports, 2015
Across the foot sole, there are vibration and monofilament sensory differences despite an alleged even distribution of cutaneous afferents. Mechanical property differences across foot sole sites have been proposed to account for these differences. Vibration (VPT; 3 Hz, 40 Hz, 250 Hz), and monofilament (MF) perception threshold measurements were compared with skin hardness, epidermal thickness, and stretch response across five foot sole locations in young healthy adults (n = 22). Perceptual thresholds were expected to correlate with all mechanical property measurements to help address sensitivity differences between sites. Following this hypothesis, the MedArch was consistently found to be the thinnest and softest site and demonstrated the greatest sensitivity. Conversely, the Heel was found to be the thickest and hardest site, and was relatively insensitive across perceptual tests. Site differences were not observed for epidermal stretch response measures. Despite an apparent trend ...
Journal of Foot and Ankle Research
Background: Ankle movements can be partially encoded by cutaneous afferents. However, little is known about the central integration of these cutaneous signals, and whether individual differences exist in this integration. The aim of this study was to determine whether the effect of cutaneous stimulation at the ankle would differ depending on the participants' preferred sensory strategy appraised by relative proprioceptive weighting (RPw). Methods: Forty-seven active young individuals free of lower-limb injury stood on a force platform either barefoot or wearing a custom-designed bootee. Vibrations (60 Hz, 0.5 mm) were applied either to the peroneal tendons or to the lumbar paraspinal muscles. Results: The barefoot RPw was strongly negatively correlated to the absolute change in RPw measured in the bootee condition (r = −0.81, P < 0.001). Participants were then grouped depending on their barefoot RPw value. The RPw was significantly higher in the bootee condition than in the barefoot condition only for participants with low barefoot RPw. Conclusions: The external cutaneous stimulation given by the bootee increased the weight of ankle proprioceptive signals only for participants with low barefoot RPw. This result confirmed that optimization of the ankle proprioceptive signals provided by cutaneous afferent stimulation has a differential effect depending on the participants' preferred sensory strategy.
Journal of applied physiology (Bethesda, Md. : 1985), 2016
It has previously been shown that cutaneous sensory input from across a broad region of skin can influence proprioception at joints of the hand. The current experiment tested whether cutaneous input from different skin regions across the foot can influence proprioception at the ankle joint. The ability to passively match ankle joint position (17° and 7° plantarflexion and 7° dorsiflexion) was measured while cutaneous vibration was applied to the sole (heel, distal metatarsals) or dorsum of the target foot. Vibration was applied at two different frequencies to preferentially activate Meissner's corpuscles (45Hz, 80μm) or Pacinian corpuscles (255Hz, 10μm) at amplitudes ~3dB above mean perceptual thresholds. Results indicated that cutaneous input from all skin regions across the foot could influence joint matching error and variability, although the strongest effects were observed with heel vibration. Furthermore, the influence of cutaneous input from each region was modulated by j...
Cutaneous afferents from human plantar sole contribute to body posture awareness
Neuroreport, 2002
We investigated whether the tactile information from the main supporting areas of the foot are used by the brain for perceptual purposes, namely body posture awareness and body representation in space. We applied various patterns of tactile stimulation to one or both soles of unmoving and blindfolded subjects by a 60 micro-vibrator tactile matrix set in a force platform. The perceptual e¡ects of the stimulation were assessed through a 3D joystick handled by the subjects. All subjects reported illusory perceptions of whole-body leaning. Both orientation and amplitude of these perceptions depended on the stimulation pattern. Additional kinesthetic illusions sometimes occurred along the longitudinal axis of the body. We conclude that foot sole input contributes to the coding and the spatial representation of body posture. NeuroReport 13:1957^1961
Distribution of Tactile Sensitivity and Elasticity in Japanese Foot Sole
KANSEI Engineering International, 2004
Tactile sensitivity of the foot was investigated using the Semmes-Weinstein monofilament method to quantify the pressure sensory threshold. Gender differences and variations in sensitivity at various sites on the foot (inter-locational sensitivity differences) were analyzed using a nonparametric test. Skin elasticity at 3 points on the sole was measured using a Venustron device (AXIOM Co.), and the relation to sensitivity was examined. Gender differences and inter-locational differences in plantar elasticity were also analyzed. Subjects were 53 male and 31 female volunteers aged between 18 and 39 years who had no known neurological dysfunction or disease. Results showed no significant gender differences in foot sensitivity but indicated significant inter-locational sensitivity differences (p<0.01). A typical pattern was observed in the distribution of sensitivity, with the dorsal region being the most sensitive, followed by the plantar arch and the side region (lateral, medial and back regions), whereas the plantar region other than the plantar arch was the least sensitive. Weight bearing locations appeared less sensitive than sites that do not bear appreciable weight. Inter-locational differences with respect to skin elasticity was significant (p<0.01), with the center of heel point being hardest , f ollowed by the plantar arch point, while the 1st metatarsal head point was softest. Although we anticipated that pressure sensory thresholds might be estimated from elasticity, the correlation between these two factors was too low to enable this. The plantar region has different sensitivity and elasticity characteristics depending on the sites of the sole and on the individual. Shoe comfort may be improved by adjusting the properties of materials forming the insole to the sensitivity and elasticity characteristics of the individual foot.
Foot callus thickness does not trade off protection for tactile sensitivity during walking
Nature, 2019
Until relatively recently, humans, similar to other animals, were habitually barefoot. Therefore, the soles of our feet were the only direct contact between the body and the ground when walking. There is indirect evidence that footwear such as sandals and moccasins were first invented within the past 40 thousand years1, the oldest recovered footwear dates to eight thousand years ago2 and inexpensive shoes with cushioned heels were not developed until the Industrial Revolution3. Because calluses—thickened and hardened areas of the epidermal layer of the skin—are the evolutionary solution to protecting the foot, we wondered whether they differ from shoes in maintaining tactile sensitivity during walking, especially at initial foot contact, to improve safety on surfaces that can be slippery, abrasive or otherwise injurious or uncomfortable. Here we show that, as expected, people from Kenya and the United States who frequently walk barefoot have thicker and harder calluses than those wh...
Normative data for cutaneous threshold and spatial discrimination in the feet
Muscle & Nerve, 2017
Introduction: No data are available for normative values of cutaneous threshold and spatial discrimination of the feet. We developed clinically applicable reference values in relation to the nerve distributions of the feet. Methods: We determined foot sensation in 196 healthy individuals. Cutaneous threshold (1-point static discrimination, S1PD) was tested with monofilaments (0.008 to 300 gram) and spatial discrimination [2-point static and moving discrimination (S2PD, M2PD)] on 5 locations per foot. Results: There was a significant age-dependent increase in S1PD, S2PD, and M2PD values (P<0.05). No significant differences were found between both feet. S1PD values differed up to 0.8 g between genders. There were no significant differences between genders for S2PD and M2PD measurements. M2PD values were generally lower than S2PD values. Discussion: This study provides age-related normative values for foot sensation to help clinicians assess sensory deficits in relation to aging and identify patients with underlying nerve problems.