Have neuroscientists been barking up the wrong tree for the last hundred years when it comes to cognitive function?
Brain activity, they say, is solely down to the complex web of connections that transmit signals linking specialized populations of cells in different regions of the brain. But game-changing new research suggests this view is mistaken.
The driver of brain function isn’t its wiring but its shape; it’s size, curves, folds, and grooves.
If true, this view could fundamentally change the way we think about psychiatric and neurological diseases such as depression, schizophrenia, and dementia, and how we treat them. Here’s the story…
In the fields of physics and engineering, a system’s function is understood through constraints imposed by its structure. Yet in neuroscience this is ignored. Instead, the brain is viewed as having discrete specialized regions, each of which carries out a specific function needed for the task in hand – thoughts, feelings, behavior, movement, speech, vision, etc. These regions communicate with each other via the cells’ axons along which nerve impulses are conducted.
But this view has been challenged by a research team in Australia.
Function Driven By Brain Waves
The researchers, which included both physicists and neuroscientists, examined more than ten thousand different maps of the brain gathered from scans from over a thousand experiments as people performed a wide range of different cognitive, emotional, sensory, and motor tasks.
From all this data they created a computer model to simulate the way the size and shape of the brain affects its brain waves. By comparing their new model to an existing model of how the brain works based on connectivity, they found shape influenced patterns of brain activity more than connections between brain regions.
Alex Fornito, senior author of the study published in the journal Nature in May explained that the “close link between geometry (shape) and function is driven by wave-like activity propagating throughout the brain, just as the shape of a pond influences the ripple patterns that are formed by a falling pebble.”
The scientists focused on a term used in physics – eigenmode – which, when referring to the brain, is a preferred pattern of vibration or excitation.
First author James Pang explains that the best way to understand this “is to think of a violin. Every time you pluck its string, it vibrates with some pattern, and this pattern corresponds to the notes that you hear. The preferred patterns of vibration are the eigenmodes of the string.
“There are many eigenmodes, and every single eigenmode encodes a different frequency. And all of them can combine in various different ways to support whatever brain processes that you can think of.
“Just as the resonant frequencies of a violin string are determined by its length, density, and tension, the eigenmodes of the brain are determined by its structural, physical, geometric, and anatomical properties.
“It means the idea that only certain neurons in a certain part of the brain are working when you do something is probably inaccurate, because other parts of the brain are also contributing.”
Consequences Are Mind-Boggling
Dr. Pang admits that what he and his colleagues are proposing is “mind-boggling” and turns conventional wisdom on its head, yet it does have a major benefit. Instead of having to understand how the brain’s 86 billion neurons linked by trillions of connections are involved in health and disease, it’s a much simpler matter to look at how waves of excitation travel through the brain.
Professor Fornito believes their findings “raise the possibility of predicting the function of the brain directly from its shape, opening new avenues for exploring how the brain contributes to individual differences in behavior and risk for psychiatric and neurological diseases.”
Dr. Pang added: “The work opens opportunities to understand the effects of diseases like dementia and stroke by considering models of brain shape. People with dementia, for example, have atrophy in certain parts of the brain, which may change the activity they can support.”
The research is still early of course, but it’s very exciting to consider that one day doctors may use your brain’s shape to predict or even treat neurological issues such as Alzheimer’s disease. We’ll be watching and keep you posted on any new discoveries in this area.
The Awakening From Alzheimer’s Team