![]() In the clinical domain, however, the term synergy is not applied uniformly. ![]() The net effect of the interaction of these constraints is a reduction in the number of degrees of freedom that are, or can be, controlled during movement execution. Importantly, a common denominator across many definitions and interpretations is that biomechanical and neural factors constrain the spatial and temporal coordination of groups of muscles and joints. Furthermore, even though several mechanisms could potentially be involved in coupling the activity of multiple muscles (e.g., reflexes, supraspinal networks, and/or spinal modules driven by supraspinal drive), these mechanisms need not be mutually exclusive. However, it has been proposed that the role of synergies may be to map high-level goals to multi-muscle activation patterns, as suggested by their sensitivity to specific task performance goals (Ting and McKay, 2007 Tresch and Jarc, 2009). ![]() Importantly, how synergies are defined or conceptualized may or may not account for how synergies are built and retrieved, or how flexible they might be. For more details on how these techniques have been applied to a large variety of motor tasks and their interpretation, the reader is referred to a recent review on the neural bases of hand synergies (Santello et al., 2013). The quest for synergies at different levels of the system has led to the development of several approaches to quantify the structure and number of synergies in a variety of tasks, including the modulation of hand posture to object geometry, digit force coordination during force production tasks for application of UCM analysis to study the effects of neurological disorders and aging on motor coordination), multi-digit force coordination during prehension, and coordination of activation across multiple muscles. Specifically, these muscle synergies have been defined as “building blocks” of complex movements that can be flexibly combined when performing different tasks, or the same task performed in different conditions, by modulating the timing and/or amplitude of EMG activity of individual muscles. This research has provided important insights into the modular nature of control of a variety of movements by identifying multi-muscle EMG patterns, i.e., muscle synergies for discussion on the modular control of movement from an evolutionary perspective, the reader is referred to a recent review by Lacquaniti et al. However, one of the most widely studied and informative domains for identifying synergies has been muscle activity, quantified as patterns of interference electromyographic (EMG) activity recorded simultaneously across multiple muscles. As noted in a recent review, this very definition of “synergy” can have different implications in terms of underlying mechanisms depending on the scale of the system at which it is applied, e.g., groups of motor units, muscles, and/or joints (Santello et al., 2013). A classic definition of synergy is “a collection of relatively independent degrees of freedom that behave as a single functional unit”. The term “synergy” – from the Greek synergia – means “working together.” The concept of multiple elements working together toward a common goal has been extensively used to develop experimental approaches and analytical techniques to understand how the central nervous system (CNS) controls movement.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |