The contribution of motor commands to position sense differs between elbow and wrist

Lee D Walsh, Uwe Proske, Trevor James Allen, Simon C Gandevia

Research output: Contribution to journalArticleResearchpeer-review

26 Citations (Scopus)

Abstract

Recent studies have suggested that centrally generated motor commands contribute to the perception of position and movement at the wrist, but not at the elbow. Because the wrist and elbow experiments used different methods, this study was designed to resolve the discrepancy. Two methods were used to test both the elbow and wrist (20 subjects each). For the wrist, subjects sat with their right arm strapped to a device that restricted movement to the wrist. Before each test, voluntary contraction of wrist flexor or extensor muscles controlled for muscle spindle thixotropy. After relaxation, the wrist was moved to a test angle. Position was indicated either with a pointer, or by matching with the contralateral wrist, under two conditions: when the reference wrist was relaxed or when its muscles were contracted isometrically (30 maximum). The elbow experiment used the same design to measure position sense in the passive elbow and with elbow muscles contracting (30 maximum). At the wrist when using a pointer, muscle contraction altered significantly the perceived wrist angle in the direction of contraction by 7 deg [3 deg, 12 deg] (mean [95 confidence interval]) with a flexor contraction and 8 deg [4 deg, 12 deg] with an extensor contraction. Similarly, in the wrist matching task, there was a change of 13 deg [9 deg, 16 deg] with a flexor contraction and 4 deg [1 deg, 8 deg] with an extensor contraction. In contrast, contraction of elbow flexors or extensors did not alter significantly the perceived position of the elbow, compared with rest. The contribution of central commands to position sense differs between the elbow and the wrist.
Original languageEnglish
Pages (from-to)6103 - 6114
Number of pages12
JournalThe Journal of Physiology
Volume591
Issue number23
DOIs
Publication statusPublished - 2013

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