A Computational Neuromusculoskeletal Model of Human Arm Movements

Abstract

This work proposes a computational neuromusculoskeletal model of human arm movements. The model consists of three components: the supraspinal neural control system, the spinal motor system, and the muscle-tendon actuation system. In the supraspinal neural system model, the cerebellum is regarded as having feedforward control and the cerebrum as feedback control principally based on the feedback-error learning scheme. This computational model proposes that the feedforward control of the cerebellum may not need to be an explicit locus of an inverse dynamic model. This model also includes the modularly organized spinal motor system such that it simplifies controlling redundant muscular actuators. Cerebellar feedforward control and the spinal motor system are assumed to be adaptive. The two motor adaptations seem to synergistically promote motion flexibility and simplify the neural system structure. The neural control system is combined with the Hill-type muscle-tendon model to generate arm movement. The overall model proposes that an approximate inverse dynamic model may implicitly be constructed over the integrated neuromusculoskeletal system, and it is not necessary to be explicitly computed in a specific motor system. To cope with the human neural system, neuromuscular activation dynamics and neural transmission delays are included in the model. A computational simulation study using the model was implemented to verify the feasibility of the model. Center out reaching movements and learning of those movements as well s generations of figure eight-like movements were computationally tested. A plausible motor control scheme of movement is discussed using the model.