Neuromuscular Junction (NMJ): Aging

Aging is associated with reduced physical activity, a loss of motor neurons, and a decrease in muscle fiber size (sarcopenia), all of which may affect long-term plasticity of neuromuscular junctions (NMJs). For each of these factors, it is essential to consider motor unit (muscle fiber) type since the properties of motor neurons and muscle fibers are precisely matched and selective motor unit recruitment is a primary mechanism by which the nervous system controls muscle contraction. This article examines age-related changes in properties of different motor unit types and how these may affect structural and functional remodeling of NMJs.