Brain's motor cortex uses multiple frequency bands to coordinate movement

February 21, 2014, RIKEN
Figure 1: Typical slow gamma (left), fast gamma (center) and theta (right) brain-wave patterns measured during voluntary actions in rats. Credit: J. Igarashi et al.

Synchrony is critical for the proper functioning of the brain. Synchronous firing of neurons within regions of the brain and synchrony between brain waves in different regions facilitate information processing, yet researchers know very little about these neural codes. Now, new research led by Tomoki Fukai of the RIKEN Brain Science Institute reveals how one region of the brain uses multiple brain-wave frequency bands to control movement.

Control of movement requires activation of numerous muscle groups in correct sequence, a function achieved by the motor cortex. To investigate the contribution of to this process, Fukai and his colleagues inserted multi-channel electrodes into the motor cortex of rats to record brain-wave patterns as the animals learned to push, hold and then pull a lever to obtain a food reward. They also developed a machine-learning technique to extract spike sequences of individual neurons from the recorded waves.

Fukai and his colleagues found that brain waves of different frequencies appeared during distinct stages of the movements. Fast gamma waves, with frequencies of around 100 hertz, were most prominent when the rats pushed or pulled the lever, whereas slow gamma waves, with frequencies of 25–40 hertz, peaked when the rats held the lever to prepare for the next pull. Theta waves (4–10 hertz) peaked while the rats held the lever, and the initiation of the pulling movement coincided with a specific phase of these oscillations (Fig. 1).

Both frequencies of were coupled to the theta waves such that the peaks of all three brain-wave frequencies occurred at the same time. The activity of different types of nerve cells in different layers of the motor cortex was also synchronized with specific -wave frequencies. Importantly, cells encoding different stages of the sequential movements fired in distinct phases of the theta waves.

The results suggest that play an important role in coordinating the neuronal activity underlying the planning and execution of voluntary movement. Theta are known to be important for the processing of spatial information in the hippocampus, but this is the first time that a similar code has been observed in the motor cortex.

"We are currently using machine-learning techniques to study how phase-locked spikes in different layers of the encode motor information," says Fukai. "We are also studying whether a similar oscillatory coordination takes place in the prefrontal cortex during decision-making."

Explore further: Fluctuations in size of brain waves contribute to information processing

More information: Igarashi, J., Isomura, Y., Arai, K., Harukuni, R. & Fukai, T. "A θ–γ oscillation code for neuronal coordination during motor behavior." The Journal of Neuroscience 33, 18515–18530 (2013) dx.doi.org/10.1523/JNEUROSCI.2126-13.2013

Related Stories

Fluctuations in size of brain waves contribute to information processing

February 8, 2013
Cyclical variations in the size of brain wave rhythms may participate in the encoding of information by the brain, according to a new study led by Colin Molter of the Neuroinformatics Japan Center, RIKEN Brain Science Institute.

Brain waves encode information as time signals

December 16, 2013
How information is processed and encoded in the brain is a central question in neuroscience, as it is essential for high cognitive function such as learning and memory. Theta-gamma oscillations are "brain waves" observed ...

Rats' and bats' brains work differently on the move

April 18, 2013
A new study of brain rhythms in bats and rats challenges a widely used model - based on studies in rodents - of how animals navigate their environment. To get a clearer picture of the processes at work in the mammal brain ...

'Brain waves' challenge area-specific view of brain activity

March 20, 2013
Our understanding of brain activity has traditionally been linked to brain areas – when we speak, the speech area of the brain is active. New research by an international team of psychologists led by David Alexander and ...

Study finds analysis of many species required to better understand the brain

April 29, 2013
To get a clear picture of how humans and other mammals form memories and find their way through their surroundings, neuroscientists must pay more attention to a broad range of animals rather than focus on a single model species, ...

Rats and men: Study finds parallels in neural processing of 'adaptive control'

October 20, 2013
People and rats may think alike when they've made a mistake and are trying to adjust their thinking.

Recommended for you

Scientists discover how brain signals travel to drive language performance

June 21, 2018
Effective verbal communication depends on one's ability to retrieve and select the appropriate words to convey an intended meaning. For many, this process is instinctive, but for someone who has suffered a stroke or another ...

Scientists discover fundamental rule of brain plasticity

June 21, 2018
Our brains are famously flexible, or "plastic," because neurons can do new things by forging new or stronger connections with other neurons. But if some connections strengthen, neuroscientists have reasoned, neurons must ...

Researchers find mechanism behind choosing alcohol over healthy rewards

June 21, 2018
A new study links molecular changes in the brain to behaviours that are central in addiction, such as choosing a drug over alternative rewards. The researchers have developed a method in which rats learn to get an alcohol ...

Waking up is hard to do: Prefrontal cortex implicated in consciousness

June 21, 2018
Philosophers have pondered the nature of consciousness for thousands of years. In the 21st century, the debate over how the brain gives rise to our everyday experience continues to puzzle scientists. To help, researchers ...

Study on instinctive behaviour elucidates a synaptic mechanism for computing escape decisions

June 21, 2018
How does your brain decide what to do in a threatening situation? A new paper published in Nature describes a mechanism by which the brain classifies the level of a threat and decides when to escape.

'Antifreeze' molecules may stop and reverse damage from brain injuries

June 21, 2018
The key to better treatments for brain injuries and disease may lie in the molecules charged with preventing the clumping of specific proteins associated with cognitive decline and other neurological problems, researchers ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

MrVibrating
not rated yet Feb 23, 2014
Great work, and i fully expect similar results will be found from prefrontal studies. More generally, i suspect that the hitherto loosely-defined bandwidths of brainwave spectra are in fact octave-bound; the current discrepancy from this median being due to the fluctuating nature of the net bandwidth, effectively a floating transposition of a four octave continuum.

I've outlined the reasons for this expectation here: http://medicalxpr...try.html ..and elsewhere wrt related articles.. suffice to say i would again expect factors of two between component freqs to represent 'zero' points in meta-information valuations.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.