Open AccessAssessing Neural Connectivity and Associated Time Delays of Muscle Responses to Continuous Position Perturbations
Author(s) -
Runfeng Tian,
Julius P. A. Dewald,
Nirvik Sinha,
Yuan Yang
Publication year - 2020
Publication title -
annals of biomedical engineering
Language(s) - English
Resource type - Journals
eISSN - 1573-9686
pISSN - 0090-6964
DOI - 10.1007/s10439-020-02573-2
Subject(s) - stretch reflex , reflex , biceps , nonlinear system , neuroscience , electromyography , control theory (sociology) , elbow , physical medicine and rehabilitation , computer science , physics , psychology , medicine , anatomy , artificial intelligence , control (management) , quantum mechanics
Both linear and nonlinear electromyographic (EMG) connectivity has been reported during the expression of stretch reflexes, though it is not clear whether they are generated by the same neural pathways. To answer this question, we aim to distinguish linear and nonlinear connectivity, as well as their delays in muscle responses, resulting from continuous elbow joint perturbations. We recorded EMG from Biceps Brachii muscle when eight able-bodied participants were performing a steady elbow flexion torque while simultaneously receiving a continuous position perturbation. Using a recently developed phase coupling metric, we estimated linear and nonlinear connectivity as well as their associated delays between Biceps EMG responses and perturbations. We found that the time delay for linear connectivity (24.5 ± 5.4 ms) is in the range of short-latency stretch reflex period (< 35 ms), while that for nonlinear connectivity (53.8 ± 3.2 ms) is in the range of long-latency stretch reflex period (40-70 ms). These results suggest that the estimated linear connectivity between EMG and perturbations is very likely generated by the mono-synaptic spinal stretch reflex loop, while the nonlinear connectivity may be associated with multi-synaptic supraspinal stretch reflex loops. As such, this study provides new evidence of the nature of neural connectivity related to the stretch reflex.