Neuromuscular electrical stimulation‐promoted plasticity of the human brain. (26th September 2019)

• Record Type: Journal Article
• Authors: Carson, Richard G.; Buick, Alison R.
• Is Part Of: Journal of physiology. Volume 599:Number 9(2021)
• Page Start: 2375
• Page End: 2399
• Publication Date: 2019-09-26
• Subjects: Physiology -- Periodicals; 612.005
• DOI: 10.1113/JP278298
• Languages: English
• ISSNs: 0022-3751

Abstract

Abstract: The application of neuromuscular electrical stimulation (NMES) to paretic limbs has demonstrated utility for motor rehabilitation following brain injury. When NMES is delivered to a mixed peripheral nerve, typically both efferent and afferent fibres are recruited. Muscle contractions brought about by the excitation of motor neurons are often used to compensate for disability by assisting actions such as the formation of hand aperture, or by preventing others including foot drop. In this context, exogenous stimulation provides a direct substitute for endogenous neural drive. The goal of the present narrative review is to describe the means through which NMES may also promote sustained adaptations within central motor pathways, leading ultimately to increases in (intrinsic) functional capacity. There is an obvious practical motivation, in that detailed knowledge concerning the mechanisms of adaptation has the potential to inform neurorehabilitation practice. In addition, responses to NMES provide a means of studying CNS plasticity at a systems level in humans. We summarize the fundamental aspects of NMES, focusing on the forms that are employed most commonly in clinical and experimental practice. Specific attention is devoted to adjuvant techniques that further promote adaptive responses to NMES thereby offering the prospect of increased therapeutic potential. The emergent theme is that an association with centrally initiated neural activity, whether this is generated in the context of NMES triggered by efferent drive or via indirect methods such as mental imagery, may in some circumstances promote the physiological changes that can be induced through peripheral electrical stimulation. Abstract : Abstract figure legend The delivery of electrical current via a peripheral nerve (or across a muscle belly) activates contractile muscle fibres indirectly by depolarizing motor axons (1b). As the sensory axons in the same mixed nerve bundle have lower activation thresholds, ascending afferent volleys are also generated at intensities of electrical stimulation that exceed themotor threshold (1a). These volleys are followed by (secondary) reafference arising from the invoked muscle contraction (2). The goal of this review is to address the means through which the sensory‐mediated consequences of the stimulation alter the state of 'sensory' networks, and induce sustained 'neuroplastic' modifications within central 'motor' networks. Figure redrawn and adapted from the author's original artwork, which is available at: https://commons.wikimedia.org/wiki/File:Neuromuscular_electrical_stimulation_promoted_brain_plasticity.jpg (original figure published under a Creative Commons Attribution‐Share Alike 4.0 International license).