The basis of voluntary movements: A groundbreaking study in ‘Science’ reveals the brain mechanisms controlling natural actions

Eight years of work. A collaboration between the Laboratory of Neuroethology of Non-Human Primates of the Department of Medicine and Surgery of the University of Parma, led by Luca Bonini, and a team from the Biorobotics Institute of the Sant'Anna School of Pisa, coordinated by Alberto Mazzoni, principal investigator at the Computational Neuroengineering Lab, with the contribution of Silvestro Micera, professor in Bioingeneering. Support from three projects funded by the European Research Council (ERC) and as many Italian national projects, including MNESYS and BRIEF. These are just some of the elements of a groundbreaking study published in Science revealing new mechanisms through which the brain controls natural actions. The results challenge some of the classical views about how the motor system works and open up possible new applications in neurorehabilitation and robotics.
Using new telemetric devices, researchers recorded the activity of hundreds of neurons from the motor regions of the brains of monkeys that were completely free to express spontaneous behaviour, such as walking, climbing, or yawning. This represented a huge step forward compared to previous studies, because the available technologies forced researchers to study immobile brains during learned and stereotyped actions. The novel approach, instead, opens the possibility to understand how the brain orchestrates spontaneous movements in natural situations.

“Our brains are constantly moving - explains Luca Bonini, head of the research project - and this new approach has changed the classical idea that specific brain regions, or even single neuronal cells, control specific actions - such as biting, drinking, or grasping. According to our results, just as the individual keys of a piano can compose many different melodies, the neurons in the motor areas of our brain create complex synergies, allowing us to organise the variety of spontaneous actions that we are capable of performing, some of which until now were even impossible to study in the laboratory”.

Collaboration with bioengineers from the Sant'Anna School in Pisa made it possible to decode the complexity of this neural activity and predict the spontaneous actions the animals were about to perform using only the signals generated by neurons.

“Our results - says Alberto Mazzoni - indicate that the neuronal activity recorded during spontaneous behaviour is much more informative than that obtained in classical laboratory contexts. This information allows us to understand how the brain controls the production of voluntary actions differently depending on the context”.

The high neurological and behavioural similarity with humans suggests that this result could have relevant clinical applications.

“The results obtained through this interdisciplinary collaboration open up new and important translational perspectives for neurotechnology and neurorehabilitation - adds Silvestro Micera - Moreover, this work is a further demonstration of the extraordinary impact that the Next Generation UE projects have had on Italian research. Our hope is to continue these collaborations thanks to new funding initiatives supported by our country”.

“We hope - conclude Francesca Lanzarini, Monica Maranesi, Elena Hilary Rondoni and Davide Albertini, co-first authors of the paper - that our approach can contribute to the transition from classical neurophysiology to neuroethology in many studies on the relationship between brain and behaviour, improving the quality of life of animals even during experiments and, consequently, the validity of the results of neuroscientific research on non-human primates, which, as this work shows, are still fundamental and irreplaceable”.

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