Sensory synergy: Modeling the neural dynamics of environmental feedback to the central nervous system

Human motions are a result of complex-neural interactions between the central nervous system (CNS), sensory and musculoskeletal systems. In this paper, we are focusing in investigating these interactions relying mainly on the concept of sensory- and muscle-synergies. We hypothesize that the CNS is processing and transferring data from sensors and muscles in a unique low-dimensional signaling to simplify the complexity of environmental inputs and to facilitate recruiting muscles patterns. A pilot study involving computing sensory and muscle synergies of seven healthy participants while performing posture balance tasks was conducted to validate our hypotheses. Changes on the participant´s muscles lengths during performing the task were used to represent proprioceptors and compute sensory synergies. The resultant muscles activities, on the other hand, were recorded and used to estimate muscle synergies. Experimental results suggest that the environmental inputs were translated into lower dimensional signals and used to move the target limb to the desired position immediately after the balance disturbance. Participants who showed better posture response were found to be likely to have a stronger correlation between the utilized sensory and muscle synergies. This preliminary study is considered fundamental to understand the neural strategies among the CNS, sensory and musculoskeletal systems.