Motor Control System for Adaptation of Healthy Individuals and Recovery of Poststroke Patients: A Case Study on Muscle Synergies

Abstract

Understanding the complex neuromuscular strategies underlying behavioral adaptation in healthy individuals and motor recovery after brain damage is essential for gaining fundamental knowledge on the motor control system. Relying on the concept of muscle synergy, which indicates the number of coordinated muscles needed to accomplish specific movements, we investigated behavioral adaptation in nine healthy participants who were introduced to a familiar environment and unfamiliar environment. We then compared the resulting computed muscle synergies with those observed in 10 moderate-stroke survivors throughout an 11-week motor recovery period. Our results revealed that computed muscle synergy characteristics changed after healthy participants were introduced to the unfamiliar environment, compared with those initially observed in the familiar environment, and exhibited an increased neural response to unpredictable inputs. The altered neural activities dramatically adjusted through behavior training to suit the unfamiliar environment requirements. Interestingly, we observed similar neuromuscular behaviors in patients with moderate stroke during the follow-up period of their motor recovery. This similarity suggests that the underlying neuromuscular strategies for adapting to an unfamiliar environment are comparable to those used for the recovery of motor function after stroke. Both mechanisms can be considered as a recall of neural pathways derived from preexisting muscle synergies, already encoded by the brain’s internal model. Our results provide further insight on the fundamental principles of motor control and thus can guide the future development of poststroke therapies.

Characterization of Forearm Muscle Activation in Duchenne Muscular Dystrophy via High-Density Electromyography: A Case Study on the Implications for Myoelectric Control

“…In the case of DMD, the intact CNS and neural pathways are acting upon a progressively limited musculoskeletal system. This may lead to progressive adaptations in the CNS, similar to those observed in stroke survivors (50) expressed via compensatory movements (51), co-contractions, and lower dimensionality. Regarding gait analysis in DMD, it was shown that gait motor control complexity is minimally affected by the disease (in the early stages) (52); however, for the more complex hand and wrist control, there is no evidence.…”

Intra-Subject and Inter-Subject Movement Variability Quantified with Muscle Synergies in Upper-Limb Reaching Movements

“…Variability is an inherent property of human movement and was described as “repetition without repetition” by Bernstein in his studies on motor control [ 58 , 59 ]. Variability could account for the redundancy of the musculoskeletal system and contributed to improving the adaptation of humans to complex and changing situations [ 60 ]. When applying these concepts to rehabilitative scenarios, patients can achieve some motor function by adopting a compensation strategy that further increases intra-subject and inter-subject variability in respect to healthy people.…”

Descripción de la discapacidad y sus determinantes en personas con hemiparesia/hemiplejia del suroccidente de Colombia

“…Por otra parte, las complicaciones clínicas reportadas en el presente estudio concuerdan con varios similares donde predominan los problemas musculoesqueléticos (contracturas, dolor articular, hombro doloroso y espasticidad) y los problemas emocionales, principalmente la depresión (11,12,34,35). Estas son frecuentes y determinan un mayor o menor grado de discapacidad (12), relacionándose en este estudio de manera significativa con la presencia de discapacidad y la mayoría de los dominios de funcionamiento, especialmente con movilidad, cuidado personal y actividades cotidianas, similar a lo descrito por Silva (36) en un estudio realizado en Brasil.…”