Nandi, Tulika;
Hortobágyi, Tibor;
van Keeken, Helco G.;
Salem, George J.;
Lamoth, Claudine J. C.
Standing task difficulty related increase in agonist-agonist and agonist-antagonist common inputs are driven by corticospinal and subcortical inputs respectively
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Media type:
E-Article
Title:
Standing task difficulty related increase in agonist-agonist and agonist-antagonist common inputs are driven by corticospinal and subcortical inputs respectively
Contributor:
Nandi, Tulika;
Hortobágyi, Tibor;
van Keeken, Helco G.;
Salem, George J.;
Lamoth, Claudine J. C.
imprint:
Springer Science and Business Media LLC, 2019
Published in:Scientific Reports
Language:
English
DOI:
10.1038/s41598-019-39197-z
ISSN:
2045-2322
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title><jats:p>In standing, coordinated activation of lower extremity muscles can be simplified by common neural inputs to muscles comprising a functional synergy. We examined the effect of task difficulty on common inputs to agonist-agonist (AG-AG) pairs supporting direction specific reciprocal muscle control and agonist-antagonist (AG-ANT) pairs supporting stiffness control. Since excessive stiffness is energetically costly and limits the flexibility of responses to perturbations, compared to AG-ANT, we expected greater AG-AG common inputs and a larger increase with increasing task difficulty. We used coherence analysis to examine common inputs in three frequency ranges which reflect subcortical/spinal (0–5 and 6–15 Hz) and corticospinal inputs (6–15 and 16–40 Hz). Coherence was indeed higher in AG-AG compared to AG-ANT muscles in all three frequency bands, indicating a predilection for functional synergies supporting reciprocal rather than stiffness control. Coherence increased with increasing task difficulty, only in AG-ANT muscles in the low frequency band (0–5 Hz), reflecting subcortical inputs and only in AG-AG group in the high frequency band (16–40 Hz), reflecting corticospinal inputs. Therefore, common neural inputs to both AG-AG and AG-ANT muscles increase with difficulty but are likely driven by different sources of input to spinal alpha motor neurons.</jats:p>