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Chiappa, A. S.

Publications and source records attributed to Chiappa, A. S..

2 recordsLinked to original sources

Acquiring musculoskeletal skills with curriculum-based reinforcement learning

Efficient musculoskeletal simulators and powerful learning algorithms provide computational tools to tackle the grand challenge of understanding biological motor control. Our winning solution for the inaugural NeurIPS MyoChallenge leverages an approach mirroring human skill learning. Using a novel curriculum learning approach, we trained a recurrent neural network to control a realistic model of the human hand with 39 muscles to rotate two Baoding balls in the palm of the hand. In agreement with data from human subjects, the policy uncovers a small number of kinematic synergies even though it is not explicitly biased towards low-dimensional solutions. However, by selectively inactivating parts of the control signal, we found that more dimensions contribute to the task performance than suggested by traditional synergy analysis. Overall, our work illustrates the emerging possibilities at the interface of muscu-loskeletal physics engines, reinforcement learning and neuro-science to advance our understanding of biological motor control.

neuroscience↗

Task-driven neural network models predict neural dynamics of proprioception

Proprioception tells the brain the state of the body based on distributed sensors in the body. However, the principles that govern proprioceptive processing from those distributed sensors are poorly understood. Here, we employ a task-driven neural network modeling approach to investigate the neural code of proprioceptive neurons in both cuneate nucleus (CN) and somatosensory cortex area 2 (S1). We simulated muscle spindle signals through musculoskeletal modeling and generated a large-scale, naturalistic movement repertoire to train thousands of neural network models on 16 behavioral tasks, each reflecting a hypothesis about the neural computations of the ascending proprioceptive pathway. We found that the networks internal representations developed through task-optimization generalize from synthetic data to predict single-trial neural activity in CN and S1 of primates performing center-out reaching. Task-driven models outperform linear encoding models and data-driven models. Behavioral tasks, which aim to predict the limb position and velocity were the best to predict the neural activity in both areas. Architectures that are better at solving the tasks are also better at predicting the neural data. Last, since task-optimization develops representations that better predict neural activity during active but not passively generated movements, we hypothesize that neural activity in CN and S1 is top-down modulated during goal-directed movements.

neuroscience↗