Brain activity showing areas for movement amplitude and speed control.

Decoding Your Movements: How Your Brain Controls Speed and Size

Lena Voss in Mind & Education December 2025 • 4 min read.

"New research unveils how different brain regions specialize in managing the amplitude and speed of our actions."

Voluntary movements, whether a delicate wrist flex or a powerful swing, require precise control. This coordination is managed by a distributed network in the brain, but a key question remains: do specific areas handle individual aspects of movement, or do they manage a blend of factors?

New research using rapid event-related functional magnetic resonance imaging (fMRI) is shedding light on this question. By examining brain activity during the encoding of movement amplitude (size), duration, and speed, scientists are uncovering the specialized roles of different brain regions.

The findings reveal a fascinating division of labor. While the primary motor cortex (M1) appears to be preferentially involved in controlling movement amplitude, the cerebellum focuses on movement speed. This specialization allows for seamless and efficient motor control.

The Brain's Movement Control Center: A Tale of Two Regions

Brain activity showing areas for movement amplitude and speed control.

The study, published in Human Brain Mapping, used a controlled single-joint wrist-flexion task to isolate and analyze brain activity. Participants performed wrist movements of varying amplitude and speed while researchers monitored their brain activity using fMRI.

The results highlighted two key areas:

Primary Motor Cortex (M1): This area showed a strong preference for encoding movement amplitude. In other words, the level of activity in M1 was closely related to the size of the wrist movement.
Cerebellum (specifically lobule V): The anterior lobe of the cerebellum showed preferential encoding of movement speed. Activity in this region was more closely linked to how quickly the wrist movement was performed.

Interestingly, other regions like the supplementary motor area (SMA), basal ganglia (putamen), and anterior intraparietal sulcus didn't show a preference for any single parameter, suggesting they might be involved in more general aspects of motor control. Also, muscle force, as measured by electromyographic data, was primarily modulated by movement amplitude, thus restricting the distinction between amplitude and muscle force encoding.

The Bigger Picture: Implications for Understanding and Improving Movement

These findings offer valuable insights into how the brain orchestrates movement. By understanding the specialized roles of different brain regions, we can gain a deeper understanding of motor control and potentially develop more effective treatments for movement disorders.

Future research could explore how these findings translate to more complex, multi-joint movements. Also, It is crucial to acknowledge that complex interactions occur, and further studies may clarify the roles of muscle force, sensory feedback, and acceleration in the observed brain activity patterns.

Ultimately, this research underscores the remarkable complexity of the motor system and the intricate coordination required for even simple movements. This knowledge could inform the design of brain-computer interfaces and rehabilitation strategies, paving the way for more precise and effective interventions.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1002/hbm.23802, Alternate LINK

Title: Preferential Encoding Of Movement Amplitude And Speed In The Primary Motor Cortex And Cerebellum

Subject: Neurology (clinical)

Journal: Human Brain Mapping

Publisher: Wiley

Authors: Alit Stark-Inbar, Eran Dayan

Published: 2017-09-08

Everything You Need To Know

What specific part of the brain controls the size of a movement?

The Primary Motor Cortex (M1) is primarily responsible for controlling movement amplitude, which is the size or extent of a movement, such as how far you flex your wrist. This means that the level of activity within the M1 directly corresponds to the size of the movement being executed. Understanding this specialized role helps us appreciate how the brain efficiently manages the different aspects of a movement, enabling us to perform actions with precision.

Which part of the brain is most responsible for controlling movement speed?

The cerebellum, specifically its anterior lobe, plays a crucial role in controlling movement speed. This brain region focuses on how quickly a movement is performed. The activity in the cerebellum is closely tied to the speed of the movement. The research highlights the cerebellum's importance in our ability to perform movements at different speeds, which is essential for various everyday activities, from walking to more complex actions.

What is meant by 'movement amplitude' in this context, and why is it important?

Movement amplitude refers to the size or extent of a movement, such as the degree to which a joint bends or a limb extends. In this context, it's specifically about the range of motion of a wrist flexion. This research shows that the Primary Motor Cortex (M1) is particularly involved in controlling this aspect. Implications of understanding amplitude control include improved understanding of how our brain plans and executes movements, which could be vital for treating conditions affecting motor control, and for enhancing the efficiency of movement.

How did the researchers study the brain's activity during movement?

The research utilizes rapid event-related functional magnetic resonance imaging (fMRI) to examine the brain's activity during movement. This technique allows scientists to observe which brain regions are active during specific motor tasks, like wrist flexions of varying amplitude and speed. By tracking brain activity while participants perform these movements, researchers could identify the roles of the Primary Motor Cortex (M1) and the cerebellum in controlling movement aspects. The use of fMRI provides crucial data for understanding the brain's complex mechanisms of movement control.

What other brain areas are involved in movement, and what do they do?

The findings suggest that brain regions such as the Supplementary Motor Area (SMA), basal ganglia (putamen), and anterior intraparietal sulcus, while involved in motor control, don't show a strong preference for amplitude or speed. The research indicates these areas might be involved in more general aspects of motor control, such as planning or coordinating movements. This understanding is significant because it provides insight into the complex, distributed network within the brain that's involved in movement.