China
Africa
Explore chapters and articles related to this topic
Whole Body Vibration, Cognition, and the Brain
Published in Redha Taiar, Christiano Bittencourt Machado, Xavier Chiementin, Mario Bernardo-Filho, Whole Body Vibrations, 2019
Eddy A. van der Zee, Marelle Heesterbeek, Oliver Tucha, Anselm B. M. Fuermaier, Marieke J. G. van Heuvelen
The skin contains many specialized mechanoreceptors that subserve “touch” sensations contributing to proprioception and motor control. Mechanoreceptors located in various layers of the skin are excited by indentation of the skin by their preferred stimulus (for example vibrations, stretching of the skin or brushing). This is followed by transferring the information to the brain via the spinal cord reaching the thalamus. From there, the information is conveyed to the sensory areas of the neocortex and other areas in the basal forebrain, cerebellum and brainstem. The four types present in the glabrous skin are the Meissner and Pacinian corpuscles, Merkel cell-neurite complexes and Ruffini endings. Most likely all these types of cutaneous mechanoreceptors respond to WBV in their own way. Meissner and Pacinian corpuscles are fast-adapting types, mainly responding at the start and the end of the skin indentation. Both respond strongly to vibratory stimuli, but the Pacinian corpuscles respond predominantly to vibration frequencies exceeding 400 Hz (but also detect vibrations starting from 150 Hz). In contrast, Meissner corpuscles are sensitive to much lower frequencies, especially those of 20–40 Hz (Roudat et al., 2012 and references therein). The Merkel cell-neurite complexes and Ruffini endings are slow-adapting types, responding for a longer duration to a continuous skin indentation. These mechanoreceptors mainly respond to stretching of the skin or brushing.
Tactile Displays in Army Operational Environments
Published in Pamela Savage-Knepshield, John Martin, John Lockett, Laurel Allender, Designing Soldier Systems, 2018
Timothy L. White, Andrea S. Krausman, Ellen C. Haas
The skin is the largest organ of the human body and for the average adult it has a surface area of about 1.8 m2 (Sherrick and Cholewiak 1986). There are three types of skin: glabrous, hairy, and mucocutaneous (Greenspan and Bolanowski 1996). Glabrous skin is the hairless skin that is found on the palms and soles, and mucocutaneous skin (for example, lips) is the skin that borders entrances to the body’s interior (Greenspan and Bolanowski 1996). Of the three types of skin, hairy skin covers most of the human body. The skin has many sensory receptors or mechanoreceptors for receiving sensations like vibration, pressure, texture, temperature, and pain. The mechanoreceptors of the skin are sensitive to mechanical pressure or deformation of the skin (Sekuler and Blake 1990). The mechanoreceptor types are defined by their rate of adaptation to pressure and vibration and their receptive field size (Greenspan and Bolanowski 1996). Adaptation is the mechanism by which mechanoreceptors respond to sustained skin indentation (Greenspan and Bolanowski 1996). The receptive field is the area of skin that generates a response in a sensory neuron when stimulated, and this area is dependent on the intensity of the stimulus (Greenspan and Bolanowski 1996). Because of the varying characteristics of mechanoreceptors and their distribution throughout the body, the perceptual resolution and sensitivity of the skin to tactile stimuli vary at different body locations, which have implications for the placement of tactile displays on the body.
Thermal Physiology and Thermoregulation
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
Skin can be divided into two basic types: glabrous and nonglabrous skin. In some disciplines, glabrous skin is referred to as acral (distal), while nonglabrous skin is labeled non-acral. Glabrous skin is smooth and hairless; the type found on the palms, soles, penis, eyelids, and lips. Glabrous skin is innervated mainly by adrenergic sympathetic vasoconstrictor nerves, which increase their tone in response to cold, causing vasoconstriction. Warm conditions increase cutaneous blood flow through passive vasodilation when adrenergic sympathetic activity decreases.37 Nonglabrous (hair-bearing) skin covering most of the body's surface is innervated by both cholinergic vasodilator and adrenergic vasoconstrictor nerves.
No change in foot soft tissue morphology and skin sensitivity after three months of using foot orthoses that alter plantar pressure
Published in Footwear Science, 2021
Joanna Reeves, Richard Jones, Anmin Liu, Leah Bent, Ana Martinez-Santos, Christopher Nester
Foot orthoses can alter the contact area at specific regions of the foot, like increase the contact area in the medial arch (Farzadi et al., 2015; McCormick et al., 2013), which could influence skin sensitivity. Skin sensitivity is comprised of both peripheral (alterations to the cutaneous mechanoreceptor activation or transmission) and central influences (cortical plastic changes based on input). Changes in contact area could alter, and potentially increase, the capacity for cutaneous mechanoreceptors to detect mechanical stimuli. There are four different classes of mechanoreceptors in glabrous skin, like on the foot sole, which respond to stretch, contact forces, vibration and pressure (Johansson et al., 1982; N. D. Strzalkowski et al., 2018). Cortical plasticity allows for the potential for increased skin sensitivity through increasing the relevant area in the primary somatosensory cortex (Björkman et al., 2009) and neurophysiological changes with training has been shown in primates following stroke (Plautz et al., 2016). Increased pressure in the medial arch could increase sensitivity due to the increases in the relative weighting given to receptors from that region, or skin sensitivity could decrease if the receptors become desensitised (Hao & Delmas, 2010). Altered stimulation of mechanoreceptors can modulate afferent feedback to the central nervous system, influencing muscle activity and movement of the lower and upper limbs (Bent & Lowrey, 2013; Fallon et al., 2005; Howe et al., 2015; Nurse & Nigg, 2001; Perry et al., 2008). Consequently, the skin’s contribution to gait and posture could be influenced with use of FOs through long term stimulation of mechanoreceptors (a response to mechanical load being elicited in mechanoreceptors repetitively over time).
Assessment of surface rendering with 1 DoF vibration
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2021
Oliver Snyder, Rebeka Almasi, Cathy Fang, Roberta L. Klatzky, George Stetten
A number of findings indicate that the vibration-sensitive PCs are critical to discrimination of finely textured surfaces. In (Mahns et al. 2006), differences in frequency discrimination between hairy and glabrous skin sites could be explained by relative contributions from afferents in the hair follicles and the deeper PCs. The firing of neural fibres from the PCs has been found to be phase-locked with the frequency of the stimulus, and there are strong correlations between the power spectra of skin vibrations and the responses of individual PC fibres when fine materials are stroked (Weber et al. 2013).
Can you see the feel? The absence of tactile cues in clothing e-commerce impairs consumer decision making
Published in International Journal of Fashion Design, Technology and Education, 2023
Julia Wilfling, George Havenith, Margherita Raccuglia, Simon Hodder
It is well-known that males and females have different comfort responses in the context of physiological/thermal comfort perception. A study by Parson (2002) reported that females have greater sensitivity to cold stimuli and less tolerance to cold discomfort and Gerrett et al. (2014) found that females have significantly warmer magnitude sensations than males. Sex differences have been further investigated in a variety of sensory tests (Boles & Givens, 2011; Chen et al., 1995; Komiyama, Kawara, & De Laat, 2007; Weinstein, 1968; Wohlert, 1996), which mostly revealed greater tactile detection sensitivity in females than in males. Gescheider, Edwards, Lackner, Bolanowski, and Verrillo (1996) conducted experiments on the glabrous (hair-free) skin of the hands and found that women have a lower threshold for detecting vibrotactile signals and, therefore, a greater tactile sensitivity than men. Furthermore, a study by Woodward (1993), investigated relationships between skin compliance, sex and tactile discriminative thresholds, and found a tendency for the hands of females to be more compliant than those of males. For the interaction of the skin with textiles, however, tactile perception differences based on sex are widely unexplored. Studies investigating sex differences in online shopping found that women are more motivated by emotional and social interaction and that they enjoy a physical evaluation of products such as seeing and feeling the product before a purchase (Cho, 2004; Dittmar, Long, & Meek, 2004; Wilfling et al., 2021). Sex is a crucial factor affecting online as well as offline purchases since most apparel pieces are specifically designed for male or female customers. Based on the observed sex differences in tactile perception, it is likely that an individual’s purchase behaviour is affected by different perceptual responses amongst males and females.