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 91亚色鈥檚 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.

, 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鈥檚 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.

鈥淲hen we move through the world, our brains don鈥檛 just plan our own actions 鈥� they also prepare for surprises,鈥� 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. 鈥淵ou鈥檙e planning where you鈥檙e going, but things might also happen in the environment,鈥� explains Michaels. 鈥淭here are people walking everywhere. You鈥檙e constantly trying to anticipate who might bump into you.鈥�

As you step into the bustling crowd, your brain begins processing visual cues 鈥� 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鈥� recent research.

Predicting the unpredictable: inside the brain鈥檚 response system

The team of researchers from Western University conducted experiments using a Kinarm robotic exoskeleton device that applied mechanical perturbations to participants鈥� 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鈥檚 prediction, participants鈥� muscles responded more efficiently, showcasing the brain鈥檚 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鈥檚 motor circuits. The study was strengthened by collaboration with leading experts at Western, including the other members of Western鈥檚 Sensorimotor Superlab, J枚rn 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.

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

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Faculty of Science prof used novel approach of applying fluid dynamics and chemistry to planetary sciences for modelling study published in Nature

Wednesday March 26, TORONTO 鈥� New research led by a 91亚色 professor sheds light on the earliest days of the Earth鈥檚 formation and potentially calls into question some earlier assumptions in planetary science about the early years of rocky planets. Establishing a direct link between the Earth鈥檚 interior dynamics occurring within the first 100 million years of its history and its present-day structure, the work is one of the first in the field to combine fluid mechanics with chemistry to better understand the Earth's early evolution. 

鈥淭his study is the first to demonstrate, using a physical model, that the first-order features of Earth鈥檚 lower mantle structure were established four billion years ago, very soon after the planet came into existence,鈥� says lead author Faculty of Science Assistant Professor in the Department of Physics and Astronomy at 91亚色.

The mantle is the rocky envelopment that surrounds the iron core of rocky planets. The structure and dynamics of the Earth鈥檚 lower mantle play a major role throughout Earth鈥檚 history as it dictates, among others, the cooling of the Earth鈥檚 core where the Earth鈥檚 magnetic field is generated.

Boukar茅 鈥� originally from France 鈥� worked with research colleagues from his former institution, Universit茅 Paris Cit茅's James Badro and Henri Samuel, on the paper, , which was published today in Nature.

Boukar茅 says that while seismology, geodynamics, and petrology have helped answer many questions about the present-day thermochemical structure of Earth鈥檚 interior, a key question remained: how old are these structures, and how did they form? Trying to answer this, he says, is much like looking at a person in the form of an adult versus a child and understanding how the energetic conditions will not be the same.

鈥淚f you take kids, sometimes they do crazy things because they have a lot of energy, like planets when they are young. When we get older, we don't do as many crazy things, because our activity or level of energy decreases. So, the dynamic is really different, but there are some things that we do when we are really young that might affect our entire life,鈥� he says 鈥淚t鈥檚 the same thing for planets. There are some aspects of the very early evolution of planets that we can actually see in their structure today.鈥�

To better understand old planets, we must first learn how young planets behave.

Since simulations of the Earth鈥檚 mantle focus mostly on present-day solid-state conditions, Boukar茅 had to develop a novel model to explore the early days of Earth when the mantle was much hotter and substantially molten, work that he has been doing since his PhD.

Boukar茅鈥檚 model is based on a multiphase flow approach that allows for capturing the dynamics of magma solidification at a planetary scale. Using his model, he studied how the early mantle transitioned from a molten to a solid state.  Boukar茅 and his team were surprised to discover that most of the crystals formed at low pressure, which he says creates a very different chemical signature than what would be produced at depth in a high-pressure environment. This challenges the prevailing assumptions in planetary sciences in how rocky planets solidify.

鈥淯ntil now, we assumed the geochemistry of the lower mantle was probably governed by high-pressure chemical reactions, and now it seems that we need to account also for their low-pressure counterparts.鈥�

Boukare says this work could also help predict the behaviour of other planets down the line.

鈥淚f we know some kind of starting conditions, and we know the main processes of planetary evolution, we can predict how planets will evolve.鈥�

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91亚色 is a modern, multi-campus, urban university located in Toronto, Ontario. Backed by a diverse group of students, faculty, staff, alumni and partners, we bring a uniquely global perspective to help solve societal challenges, drive positive change, and prepare our students for success. 91亚色's fully bilingual Glendon Campus is home to Southern Ontario's Centre of Excellence for French Language and Bilingual Postsecondary Education. 91亚色鈥檚 campuses in Costa Rica and India offer students exceptional transnational learning opportunities and innovative programs. Together, we can make things right for our communities, our planet, and our future. 

Media Contact: 

Emina Gamulin, 91亚色 Media Relations, 437-217-6362, egamulin@yorku.ca

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