Abstract
Functional Electrical Stimulation (FES) has demonstrated to improve walking ability and to induce the carryover effect, long-lasting persisting improvement. Functional magnetic resonance imaging has been used to investigate effective connectivity differences and longitudinal changes in a group of chronic stroke patients that attended a FES-based rehabilitation program for foot-drop correction, distinguishing between carryover effect responders and non-responders, and in comparison with a healthy control group. Bayesian hierarchical procedures were employed, involving nonlinear models at within-subject level—dynamic causal models—and linear models at between-subjects level. Selected regions of interest were primary sensorimotor cortices (M1, S1), supplementary motor area (SMA), and angular gyrus. Our results suggest the following: (i) The ability to correctly plan the movement and integrate proprioception information might be the features to update the motor control loop, towards the carryover effect, as indicated by the reduced sensitivity to proprioception input to S1 of FES non-responders; (ii) FES-related neural plasticity supports the active inference account for motor control, as indicated by the modulation of SMA and M1 connections to S1 area; (iii) SMA has a dual role of higher order motor processing unit responsible for complex movements, and a superintendence role in suppressing standard motor plans as external conditions changes.
Highlights
The healthy control group was composed by 16 healthy volunteers (8 males), right as the result from STEP 1, except having possibly different weights over the different handed, with no neurological or orthopedic impairment
(iv) We suggest that the mechanism of action of Functional Electrical Stimulation (FES) carryover is based on movement prediction and sense of agency or body ownership
We presented a Dynamic Causal Modeling (DCM)-based hierarchical approach including M1, S1, supplementary motor area (SMA), and Angular gyrus (AG)
Summary
Strokes are one of the main causes of long-term disability worldwide. As most patients survive the initial injury, the biggest drawback is usually through long-term impairment. When coming to motor impairment, most post-stroke patients recover at least some of their lost motor functions, though the degree of this recovery is variable, depending on several factors including the severity of the damage, the type and intensity of rehabilitation therapy and the commitment of the subject [1,2]. When dealing in particular with Functional Electrical Stimulation (FES) treated foot drop issue, the application of the peroneal nerve stimulation has a positive well-known orthotic effect [3], but a proportion of patients are able to relearn the ability to voluntarily dorsiflex the ankle without the device, as first observed by Liberson and colleagues [4]
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