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  • Mélanie Henry,
  • Jacques Duchateau,
  • Stéphane Baudry
Mélanie Henry
Université Libre de Bruxelles

Corresponding Author:[email protected]

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Jacques Duchateau
Université Libre de Bruxelles
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Stéphane Baudry
Université Libre de Bruxelles
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Ageing is accompanied by numerous changes within the sensory and motor component of the muscle spindle pathway. To further document these age-related changes, this study compared the characteristics of the Hoffmann (H) reflex and M wave, evoked with several pulse durations, between young and old adults. The H-reflex and M-wave recruitment curves were analysed from recordings performed at rest in the flexor carpi radialis of 12 young (21-36 yrs) and 12 old adults (62-80 yrs). For each pulse duration (0.05-ms, 0.2-ms, and 1-ms), the maximal H-reflex amplitude (HMAX), the associated M wave (MHmax), and the H-reflex amplitude for a stimulus intensity evoking an M-wave of 5% MMAX (HM5%) were measured. The strength-duration time constant and response threshold were estimated from the charge/stimulus-duration relation for H reflex and M wave. The main results indicate that varying pulse duration mainly induces similar effect on H-reflex and M-wave recruitment curves between young and old adults. However, regardless of pulse duration, old adults had lesser HMAX (p = 0.029) but greater HM5% (p<0.001) and MHmax (p<0.001). The strength-duration time constant was lesser in old than young adults for the H reflex (p=0.048) but not the M wave (p=0.21). The H-reflex and M-wave response thresholds were greater in old than young adults (p=0.003). These results suggest greater age-related changes in the sensory than motor component of the H-reflex pathway, which may be indicative of a greater loss of sensory than motor axons or alterations of synapses between Ia afferents and motor neurones.
15 Dec 2022Submitted to European Journal of Neuroscience
19 Dec 2022Submission Checks Completed
19 Dec 2022Assigned to Editor
20 Dec 2022Review(s) Completed, Editorial Evaluation Pending
21 Jan 2023Reviewer(s) Assigned
13 Mar 2023Editorial Decision: Revise Minor
29 Mar 20231st Revision Received
30 Mar 2023Submission Checks Completed
30 Mar 2023Assigned to Editor
30 Mar 2023Review(s) Completed, Editorial Evaluation Pending
30 Mar 2023Reviewer(s) Assigned
24 Apr 2023Editorial Decision: Accept