The brain maintains multiple representations of the self for movement control

What is it about?

Our brain and nervous system continuously estimate the current state of our body and the environment to control movement. For example, we respond differently to imbalance when walking versus riding a bicycle, and leaning against a wall suppresses our balance corrections. It is unclear, however, whether these inferences of how to respond to perturbations are made centrally and shared across different movement responses, or if they operate in parallel. In this study, we used a robotic balance simulator to subtly or explicitly remove active control over whole-body movement while standing. Participants first learned a Pavlovian response: after hearing a sound cue, their balance was perturbed by the robot. When the control over whole-body movement was explicitly removed, responses were suppressed as expected. However, in trials where the control over movement was removed without telling participants, the learned correction after hearing the sound persisted. This modulation differs strikingly from sensory-evoked responses, which are known to be suppressed when the control over movement is removed. These results suggest that mechanisms responsible for these responses do not share a single, central estimation of their relevance to postural control, and may instead operate in parallel.

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Photo by Jesse Ballantyne on Unsplash

Photo by Jesse Ballantyne on Unsplash

Why is it important?

This finding challenges the view that we have a single, coherent view of our environment and ourself to control our movement. Instead, multiple representations may be used in parallel for different functions. Understanding how we form internal representations of our body and the environment is important to consider when creating unified explanations for different movement systems.