Flexible representation of dynamics allows precise tuning to the environment

Abstract

To precisely control our movements, the sensorimotor control system builds representations of the external world. However, the neural encoding of these representations - whether we encode our control as a function of specific kinematic or kinetic variables - and how we might then use these representations to build up complex actions is still unknown. Each prior study has provided support for a different reference frame or proposed mixture models to explain the complex findings. Here, we propose a different framework in which the sensorimotor control system uses multiple representations, allowing it to flexibly tune its representations to task demands. We directly test this by showing that the representation of external forces is totally governed by the nature of the experienced forces. Participants form a global force representation based on the coordinate system that best explains the forces experienced at different arm postures. We suggest that when formalizing such global representation, the system decides on the representation by considering the level of uncertainty it has in each of the coordinate systems. This flexibility and redundancy in the representations allows the precise tuning to any specific task within our complex environment, explaining our expertise in a wide range of tasks. Significance StatementThe coordinate representation used for the planning and control of movement has long been a fundamental question in neuroscience. While many studies have investigated the representation of external dynamics to answer this question, there exists no coherent view of the coordinate frame used for this representation. We show that this inconsistency arises because the nervous system has multiple representations, combining them depending on the experienced environmental forces. This flexibility in the representation of the environmental dynamics allows precise adaptation to the complex and changing dynamics of our world.