Scanning Electron Microscopy of the Basal Surface of the Epidermis of Human Digits

Yamada, Nanako; Kashima, Yuzuru; Inoue, Taeko

doi:10.1159/000147812

Cited by 13 publications

(17 citation statements)

References 4 publications

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“…The finding that smaller fingers have better acuity suggests an inverse relationship between finger size and the density of Merkel cells, the putative mechanotransducers for statically impressed stimuli (Iggo and Muir, 1969;Ogawa, 1996;Johnson, 2001). Given that Merkel cells cluster around the bases of sweat pores in the deep epidermis (Yamada et al, 1996), we reasoned that sweat pore density would provide a measurable correlate of Merkel cluster density. High-resolution scans revealed that sweat pore density is indeed greater in smaller fingers (Fig.…”

Section: Resultsmentioning

confidence: 99%

Diminutive Digits Discern Delicate Details: Fingertip Size and the Sex Difference in Tactile Spatial Acuity

Peters¹,

Hackeman²,

Goldreich³

2009

J. Neurosci.

187

149

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We have observed that passive tactile spatial acuity, the ability to resolve the spatial structure of surfaces pressed upon the skin, differs subtly but consistently between the sexes, with women able to perceive finer surface detail than men. Eschewing complex central explanations, we hypothesized that this sex difference in somatosensory perception might result from simple physical differences between the fingers of women and men. To investigate, we tested 50 women and 50 men on a tactile grating orientation task and measured the surface area of the participants' index fingertips. In subsets of participants, we additionally measured finger skin compliance and optically imaged the fingerprint microstructure to count sweat pores. We show here that tactile perception improves with decreasing finger size, and that this correlation fully explains the better perception of women, who on average have smaller fingers than men. Indeed, when sex and finger size are both considered in statistical analyses, only finger size predicts tactile acuity. Thus, a man and a woman with fingers of equal size will, on average, enjoy equal tactile acuity. We further show that sweat pores, and presumably the Merkel receptors beneath them, are packed more densely in smaller fingers.

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Section: Resultsmentioning

confidence: 99%

Diminutive Digits Discern Delicate Details: Fingertip Size and the Sex Difference in Tactile Spatial Acuity

Peters¹,

Hackeman²,

Goldreich³

2009

J. Neurosci.

187

149

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“…In contrast to sensory nerves, autonomic nerves never innervate the epidermis in mammals. Sensory nerves innervate the epidermis and dermis as well as the subcutaneous fatty tissue as a three-dimensional network (425,881,951). Most of the nerve fibers are found in the mid-dermis and the papillary dermis.…”

Section: A Neuroanatomy and Neurophysiology Of Cutaneous Nervesmentioning

confidence: 99%

Neuronal Control of Skin Function: The Skin as a Neuroimmunoendocrine Organ

Roosterman¹,

Goerge

Schneider

et al. 2006

Physiological Reviews

556

521

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This review focuses on the role of the peripheral nervous system in cutaneous biology and disease. During the last few years, a modern concept of an interactive network between cutaneous nerves, the neuroendocrine axis, and the immune system has been established. We learned that neurocutaneous interactions influence a variety of physiological and pathophysiological functions, including cell growth, immunity, inflammation, pruritus, and wound healing. This interaction is mediated by primary afferent as well as autonomic nerves, which release neuromediators and activate specific receptors on many target cells in the skin. A dense network of sensory nerves releases neuropeptides, thereby modulating inflammation, cell growth, and the immune responses in the skin. Neurotrophic factors, in addition to regulating nerve growth, participate in many properties of skin function. The skin expresses a variety of neurohormone receptors coupled to heterotrimeric G proteins that are tightly involved in skin homeostasis and inflammation. This neurohormone-receptor interaction is modulated by endopeptidases, which are able to terminate neuropeptide-induced inflammatory or immune responses. Neuronal proteinase-activated receptors or transient receptor potential ion channels are recently described receptors that may have been important in regulating neurogenic inflammation, pain, and pruritus. Together, a close multidirectional interaction between neuromediators, high-affinity receptors, and regulatory proteases is critically involved to maintain tissue integrity and regulate inflammatory responses in the skin. A deeper understanding of cutaneous neuroimmunoendocrinology may help to develop new strategies for the treatment of several skin diseases.

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“…Training reportedly improves the tactile discrimination of frequency (Harris et al, 2001;Imai et al, 2003), dot location (Sathian and Zangaladze, 1998;Grant et al, 2000;Kauffman et al, 2002), roughness (Sathian and Zangaladze, 1997;Harris et al, 2001), punctate pressure (Harris et al, 2001), and electrotactile patterns (Weiss et al, 2007). In contrast, several studies have reported that GOT performance improves little, if at all, with repeated testing (Van Boven and Johnson, 1994;Goldreich and Kanics, 2003;Wong et al, 2011b; but see Sathian and Zangaladze, 1997).…”

Section: Tactile Perception Improves With Trainingmentioning

confidence: 99%

A Physical Constraint on Perceptual Learning: Tactile Spatial Acuity Improves with Training to a Limit Set by Finger Size

Wong

Peters²,

Goldreich

2013

J. Neurosci.

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In touch as in vision, perceptual acuity improves with training to an extent that differs greatly across people; even individuals with similar initial acuity may undergo markedly different improvement with training. What accounts for this variability in perceptual learning? We hypothesized that a simple physical characteristic, fingertip surface area, might constrain tactile learning, because previous research suggests that larger fingers have more widely spaced mechanoreceptors. To test our hypothesis, we trained 10 human participants intensively on a tactile spatial acuity task. During 4 d, participants completed 1900 training trials (38 50-trial blocks) in which they discriminated the orientation of square-wave gratings pressed onto the stationary index or ring finger, with auditory feedback provided to signal correct and incorrect responses. We progressively increased task difficulty by shifting to thinner groove widths whenever participants achieved Ն90% correct block performance. We took optical scans to measure surface area from the distal interphalangeal crease to the tip of the finger. Participants' acuity improved markedly on the trained finger and to a lesser extent on the untrained finger. Crucially, we found that participants' tactile spatial acuity improved toward a theoretical optimum set by their finger size; participants with worse initial performance relative to their finger size improved more with training, and posttraining performance was better correlated than pretraining performance with finger size. These results strongly support the hypothesis that tactile perceptual learning is limited by finger size. We suspect that analogous physical constraints on perceptual learning will be found in other sensory modalities.

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Scanning Electron Microscopy of the Basal Surface of the Epidermis of Human Digits

Cited by 13 publications

References 4 publications

Diminutive Digits Discern Delicate Details: Fingertip Size and the Sex Difference in Tactile Spatial Acuity

Diminutive Digits Discern Delicate Details: Fingertip Size and the Sex Difference in Tactile Spatial Acuity

Neuronal Control of Skin Function: The Skin as a Neuroimmunoendocrine Organ

A Physical Constraint on Perceptual Learning: Tactile Spatial Acuity Improves with Training to a Limit Set by Finger Size

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