Force perception at the shoulder after a unilateral suprascapular nerve block
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There are two key sources of information that can be used to match forces—the centrally generated sense of effort and afferent signals from mechanical receptors located in peripheral tissues. There is currently no consensus on which source of information is more important for matching forces. The corollary discharge hypothesis argues that subjects match forces using the centrally generated sense of effort. The purpose of this study was to investigate force matching at the shoulder before and after a suprascapular nerve block. The nerve block creates a sensory and muscle force mismatch between sides when matching loads. The torque matching accuracy did not change after the nerve block was administered. Directionally, the torque error was in the direction proposed by the corollary discharge hypothesis. However, the mismatch between deltoid EMG was substantially greater compared to the changes in the torque matching error after the block. The results support that sensory information is used during force matching tasks. However, since the nerve block also created a sensory disruption between sides, it is not clear how sensory information is reweighted following the nerve block and a role for sense of effort is still implicated.
KeywordsSupraspinatus Isometric ramp contraction Deltoid EMG Suprascapular nerve Force perception
Research reported in this publication was partially supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) of the National Institutes of Health (NIH) under award number 5R01AR063713.
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Conflict of interest
The authors have no conflicts of interest to disclose.
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