| Directional sensitivity along the upper limb in humans. | |
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MedLine Citation:
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PMID: 2048360 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The capacity of four neurologically healthy young adults to distinguish opposing directions of cutaneous motion was determined at five different sites along the proximal-distal axis of the upper limb. Constant-velocity brushing stimuli (ranging from 0.5 to 32.0 cm/sec) were delivered through an aperture in a Teflon plate that was securely positioned in light contact with the skin. In one series of experiments, directional sensitivity in d' units was assessed at each site, using an aperture length of 0.75 cm. In a second series of experiments, the aperture length required to obtain the same criterion level of directional sensitivity at each site was determined. To attain the sensitivity reached at distal sites, a proximal stimulus had to traverse a longer chord of skin. Specifically, chords 5.9 times longer on average (range = 5.4-6.2) were required on the proximal forearm than on the index finger pad. This finding suggests that relative directional sensitivity increases sixfold from the proximal forearm to the finger pad. Moreover, relative directional sensitivity on the shoulder was comparable to that observed on the proximal forearm for two of the subjects, and approximately one-half that observed on the proximal forearm for the other two subjects. In addition to such a prominent spatial gradient in relative directional sensitivity, the velocity of stimulus motion at which directional sensitivity was highest increased systematically as the test site was shifted from the finger pad to the proximal forearm. Specifically, the optimal velocity on the finger pad varied among subjects from 1.5 to 9.4 cm/sec (mean = 5.4 cm/sec), and on the proximal forearm from 11.5 to 31.2 cm/sec (mean = 18.6 cm/sec). The optimal velocity on the shoulder was not significantly different from that observed on the proximal forearm. The results suggest that effective and informed clinical testing of patients' capacity to distinguish opposing directions of motion on cutaneous regions that differ in peripheral innervation density requires appreciation of the sensitivities of different skin regions, as well as the unique velocity dependency of direction discrimination at each skin site. |
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Authors:
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G K Essick; K R Bredehoeft; D F McLaughlin; J A Szaniszlo |
Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Somatosensory & motor research Volume: 8 ISSN: 0899-0220 ISO Abbreviation: Somatosens Mot Res Publication Date: 1991 |
Date Detail:
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Created Date: 1991-07-18 Completed Date: 1991-07-18 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 8904127 Medline TA: Somatosens Mot Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 13-22 Citation Subset: IM; S |
Affiliation:
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Dental Research Center, University of North Carolina, Chapel Hill 27599-7455. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adolescent Adult Arm / innervation* Arousal / physiology Female Humans Mechanoreceptors / physiology* Orientation / physiology* Psychophysics Reaction Time / physiology Sensory Thresholds / physiology Skin / innervation* Touch / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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DE07509/DE/NIDCR NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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