Study illuminates the brain’s predictive power in movement control

New findings reveal how sensory expectations help the brain prepare for disturbances, enabling seamless movement in complex environments

A groundbreaking study led by Jonathan Michaels, a Faculty of Health professor at York’s School of Kinesiology and Health Science, reveals how the brains of humans and monkeys use sensory expectations to prepare for unexpected disturbances, enabling faster and more accurate motor responses.

Published today in the prestigious journal Nature, the study demonstrates that motor circuits across the brain do not passively wait for sensory signals. Instead, they proactively anticipate potential challenges, configuring themselves to respond effectively to disturbances. The research represents a significant leap forward in uncovering the brain’s predictive capabilities and its role in motor control.

This advancement provides a clearer picture of the neural mechanisms underlying movement preparation and response, illustrating how expectation itself enhances precision and stability. The discovery opens new pathways for improving rehabilitation techniques and advancing brain-computer interface technology.

“When we move through the world, our brains don’t just plan our own actions — they also prepare for surprises,” says Michaels. Imagine yourself standing at the entrance to a packed live music venue. You check your ticket and plan the most direct route to your seat. “You’re planning where you’re going, but things might also happen in the environment,” explains Michaels. “There are people walking everywhere. You’re constantly trying to anticipate who might bump into you.”

As you step into the bustling crowd, your brain begins processing visual cues — excited concertgoers, empty cups strewn about and other obstacles in your way. Without conscious effort, your brain anticipates potential disturbances and prepares to respond. When a person walks into you, your brain quickly adjusts your muscle activity to keep you on track. This seamless ability to predict and adapt to unexpected challenges reflects the findings of Michaels’ recent research.

Predicting the unpredictable: inside the brain’s response system

The team of researchers from Western University conducted experiments using a Kinarm robotic exoskeleton device that applied mechanical perturbations to participants’ arms. By providing visual cues about the likelihood of disturbances, the researchers observed that both humans and monkeys adjusted their movements based on these probabilities. When the disturbance matched the brain’s prediction, participants’ muscles responded more efficiently, showcasing the brain’s ability to use sensory expectations to optimize motor control.

To uncover the neural mechanisms behind this phenomenon, the team recorded activity from thousands of neurons in monkeys performing the tasks. The data revealed that motor circuits represent sensory expectations as simple patterns of neural activity, directly reflecting the likelihood of each possible event. These findings were further validated through computer models of the arm, which developed similar predictive strategies when trained under comparable conditions.

Conducted while Michaels was a Banting Fellow in the lab of Andrew Pruszynski, a Canada Research Chair in sensorimotor neuroscience and Schulich School of Medicine & Dentistry professor, the research benefited from cutting-edge Neuropixels technology, which enabled the simultaneous recording of hundreds of neurons, providing unprecedented insights into the brain’s motor circuits. The study was strengthened by collaboration with leading experts at Western, including the other members of Western’s Sensorimotor Superlab, Jörn Diedrichsen, Western Research Chair for motor control & computational neuroscience, and psychology professor Paul Gribble.

The implications of this research are far-reaching. By understanding how the brain uses sensory expectations to prepare for disturbances, scientists can develop innovative approaches to stroke and injury rehabilitation, helping patients regain motor function more effectively. The findings could also inform the development of brain-computer interfaces, like those currently being pioneered by Neuralink, Paradromics, Synchron and others based on decades of neuroscience research.

“This study, which took years of effort, highlights how much we still have to learn about how the brain works — and it underscores the importance of basic research in making such discoveries,” says Michaels.