Involvement of Cutaneous Sensory Corpuscles in Non-Painful and Painful Diabetic Neuropathy

Distal diabetic sensorimotor polyneuropathy (DDSP) is the most prevalent form of diabetic neuropathy, and some of the patients develop gradual pain. Specialized sensory structures present in the skin encode different modalities of somatosensitivity such as temperature, touch, and pain. The cutaneous sensory structures responsible for the qualities of mechanosensitivity (fine touch, vibration) are collectively known as cutaneous mechanoreceptors (Meissner corpuscles, Pacinian corpuscles, and Merkel cell–axonal complexes), which results are altered during diabetes. Here, we used immunohistochemistry to analyze the density, localization within the dermis, arrangement of corpuscular components (axons and Schwann-like cells), and expression of putative mechanoproteins (PIEZO2, ASIC2, and TRPV4) in cutaneous mechanoreceptors of subjects suffering clinically diagnosed non-painful and painful distal diabetic sensorimotor polyneuropathy. The number of Meissner corpuscles, Pacinian corpuscles, and Merkel cells was found to be severely decreased in the non-painful presentation of the disease, and almost disappeared in the painful presentation. Furthermore, there was a marked reduction in the expression of axonal and Schwann-like cell markers (with are characteristics of corpuscular denervation) as well as of all investigated mechanoproteins in the non-painful distal diabetic sensorimotor polyneuropathy, and these were absent in the painful form. Taken together, these alterations might explain, at least partly, the impairment of mechanosensitivity system associated with distal diabetic sensorimotor polyneuropathy. Furthermore, our results support that an increasing severity of DDSP may increase the risk of developing painful neuropathic symptoms. However, why the absence of cutaneous mechanoreceptors is associated with pain remains to be elucidated.

Tactile design of manipulator fingers based on fingertip/textilefriction-induced vibration stimulations

Textile-like soft and flexible products are widely used in our daily life. Understanding the relationship between the tactilesensations of textiles and the tactile stimuli is essential for developing humanoid robot’s finger haptic system, especiallyfor certain kind of robot systems such as service robots and exploratory robots. This paper built a frequency space thatcan qualitatively represent a roughness sensation of textiles by a developing independently random match algorithm incombination with neurophysiological features of cutaneous mechanoreceptors. The experimental results show that thesum of amplitude in frequency range between 18 and 118 Hz can effectively describe the roughness sensory of textilewith accuracies of 98.5%. In other words, by applying the sum of amplitude in frequency range between 18 and 118 Hzcould successfully match roughness sensation of textiles, and it will help engineer of humanoid robot design manipulatorfinger haptic system in textile field.

Piezo2 integrates mechanical and thermal cues in vertebrate mechanoreceptors

Tactile information is detected by thermoreceptors and mechanoreceptors in the skin and integrated by the central nervous system to produce the perception of somatosensation. Here we investigate the mechanism by which thermal and mechanical stimuli begin to interact and report that it is achieved by the mechanotransduction apparatus in cutaneous mechanoreceptors. We show that moderate cold potentiates the conversion of mechanical force into excitatory current in all types of mechanoreceptors from mice and tactile-specialist birds. This effect is observed at the level of mechanosensitive Piezo2 channels and can be replicated in heterologous systems using Piezo2 orthologs from different species. The cold sensitivity of Piezo2 is dependent on its blade domains, which render the channel resistant to cold-induced perturbations of the physical properties of the plasma membrane and give rise to a different mechanism of mechanical activation than that of Piezo1. Our data reveal that Piezo2 is an evolutionarily conserved mediator of thermal–tactile integration in cutaneous mechanoreceptors.

WHAT IN THE “HEEL” DO THEY FEEL? 15303

INTRODUCTION A typical gait pattern includes a heel strike, followed by a smooth transition to foot flat through loading response. Children with poor postural control and related gait deficits often present with anterior weight lines, which result in loss of first rocker and/or a fast transition from initial contact to footflat. The foot has many important jobs, including providing proprioceptive feedback. There are 104 cutaneous mechanoreceptors on the plantar surface of the foot.1 While most of the sensors are in the metatarsal/tarsal and toe regions, we cannot forget the role of the mechanoreceptors in the heel. Abstract PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/32044/24458 How to cite: Smith M. WHAT IN THE “HEEL” DO THEY FEEL? 15303. CANADIAN PROSTHETICS & ORTHOTICS JOURNAL, VOLUME 1, ISSUE 2, 2018; ABSTRACT, ORAL PRESENTATION AT THE AOPA’S 101ST NATIONAL ASSEMBLY, SEPT. 26-29, VANCOUVER, CANADA, 2018. DOI: https://doi.org/10.33137/cpoj.v1i2.32044 Abstracts were Peer-reviewed by the American Orthotic Prosthetic Association (AOPA) 101st National Assembly Scientific Committee. http://www.aopanet.org/

Kinematics of unconstrained tactile texture exploration

A hallmark of tactile texture exploration is that it involves movement between skin and surface. When we scan a surface, small texture-specific vibrations are produced in the skin, and specialized cutaneous mechanoreceptors convert these vibrations into highly repeatable, precise, and informative temporal spiking patterns in tactile afferents. Both texture-elicited vibrations and afferent responses are highly dependent on exploratory kinematics, however; indeed, these dilate or contract systematically with decreases or increases in scanning speed, respectively. These profound changes in the peripheral response that accompany changes in scanning speed and other parameters of texture scanning raise the question as to whether exploratory behaviors change depending on what surface is explored or what information is sought about that surface. To address this question, we measure and analyze the kinematics as subjects explore textured surfaces to evaluate different types of texture information, namely the textures' roughness, hardness, and slipperiness. We find that the exploratory movements are dependent both on the perceptual task, as has been previously shown, but also on the texture that is scanned. We discuss the implications of our findings regarding the neural coding and perception of texture.