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The human brain flexibly fulfils numerous cognitive roles that are essential for survival, such as memory, attention and sensory processing. However, little is known about the organisational framework that ensures that these functions get carried out within specific timeframes.
The team analysed five large magnetoencephalography (MEG) datasets, with brain activity recordings from more than 800 people, to study the activity of large cortical brain networks. They found that although networks do not activate in a strict order, they do tend to activate in a characteristic pattern that repeats cyclically every 300–1,000 milliseconds.
The strength and speed of the cycles identified were found to be influenced by genetics, and closely associated with several factors. For example, faster reaction times are associated with stronger cycles, with fewer deviations from the characteristic pattern, demonstrating their relevance for cognitive performance; and older individuals exhibit slower cycles, aligning with observations of age-related cognitive slowing.
The study was published in the journal Nature Neuroscience and conducted at the University of Oxford’s Department of Psychiatry, in collaboration with the University of Birmingham, Aarhus University in Denmark, and industry partner Resonait Medical Technologies.
Lead author Dr Mats Van Es, Postdoctoral Researcher at the University of Oxford, said:
This is a pivotal finding in our understanding of brain function, showing that the brain’s functional networks are organised into periodic cycles.
“The study shows that these cyclical dynamics occur not only at rest but also when replaying memories and during other cognitive tasks, where they predict response speed.
“This suggests that the brain’s cyclical organisation is a fundamental way of coordinating cognitive functions on a moment-to-moment basis.”
This finding could have implications for research into brain-related illnesses and the treatments available for them. For example, the research team’s industry partner Resonait is seeking to improve an existing neurostimulation treatment for depression by coordinating the stimulation timing with these cyclical patterns.
Senior author Professor Mark Woolrich, Director of the Oxford Centre for Human Brain Activity at Oxford’s Department of Psychiatry, where the research took place, said:
Cycles are ubiquitous in biological systems. The cycles we have found in awake brain activity likely serve the need for crucial cognitive functions to be periodically activated, akin to the structured stages of a sleep cycle, albeit on a much faster timescale.
As in sleep, disruption of the cycles could be an important marker of brain disorders, and cycle-related measures could inform future clinical applications.”
Video transcript:
How does the brain ensure that all essential cognitive functions are fulfilled within a reasonable period?
We studied transitions between large-scale cortical networks. Each network is characterised by a spatial/spectral distribution of power/connectivity.
We found that transitions between these networks is not random.
Large-scale functional brain networks activate in cycles. <image of a 12 point circle with static arrows between numbers and a red arrow constantly circling the numbers like on a clock>
While there is always a tendency for cycles to have the same ordering of networks, the ordering does vary to some extent between cycles.
The speed, strength and phase of the cycle are related to age, genetics, cognition and behaviour.
This combination of order and variability represents the need for the brain to perform all essential roles in a timely manner, while maintaining its flexibility and adaptability.