Role of descending control during coactivation in long-latency responses

Determine how descending control and the coordination of coactivated agonist and antagonist muscles contribute to long-latency proprioceptive responses (LLRmechanical) that accommodate features of the task, body, and environment.

Background

Long-latency responses to mechanical perturbations involve transcortical pathways and are known to flexibly reflect task goals, limb biomechanics, and environmental context. However, prior studies have typically used paradigms emphasizing an agonist muscle under background load with reciprocal inhibition of the antagonist.

The authors note that muscle coactivation demands active and reciprocal excitation of agonist and antagonist muscles, making it unclear how descending pathways coordinate these muscles to produce functional long-latency responses under coactivation.