Corniani, G. and Saal, H.P. orcid.org/0000-0002-7544-0196 (2020) Tactile innervation densities across the whole body. Journal of Neurophysiology, 124 (4). pp. 1229-1240. ISSN 0022-3077
Abstract
The skin is our largest sensory organ and innervated by afferent fibers carrying tactile information to the spinal cord and onto the brain. The density with which different classes of tactile afferents innervate the skin is not constant but varies considerably across different body regions. However, precise estimates of innervation density are only available for some body parts, such as the hands, and estimates of the total number of tactile afferent fibers are inconsistent and incomplete. Here we reconcile different estimates and provide plausible ranges and best estimates for the number of different tactile fiber types innervating different regions of the skin, using evidence from dorsal root fiber counts, microneurography, histology, and psychophysics. We estimate that the skin across the whole body of young adults is innervated by approximately 230,000 tactile afferent fibers (plausible range: 200,000-270,000), with a subsequent decrement of 5-8% every decade due to aging. 15% of fibers innervate the palmar skin of both hands and 19% the region surrounding the face and lips. Slowly and fast-adapting fibers are split roughly evenly, but this breakdown varies with skin region. Innervation density correlates well with psychophysical spatial acuity across different body regions, and additionally, on hairy skin, with hair follicle density. Innervation density is also weakly correlated with the size of the cortical somatotopic representation, but cannot fully account for the magnification of the hands and the face.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 the Authors. Licensed under Creative Commons Attribution CC-BY 4.0. Published by the American Physiological Society. (http://creativecommons.org/licenses/by/4.0/deed.en_US) |
Keywords: | cutaneous afferent; mechanoreceptor; glabrous skin; hairy skin; homunculus |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Psychology (Sheffield) |
Funding Information: | Funder Grant number WELLCOME TRUST (THE) 209998/Z/17/Z EUROPEAN COMMISSION - HORIZON 2020 813713 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 13 Oct 2020 16:51 |
Last Modified: | 26 Oct 2020 17:16 |
Status: | Published |
Publisher: | American Physiological Society |
Refereed: | Yes |
Identification Number: | 10.1152/jn.00313.2020 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:166148 |