As the heart beats, the brain pulses, too, making micro-movements not visible to the naked eye.
Thanks to new ways of amplifying MRI scans, researchers are now able to study these tiny movements and fluid shifts, and are exploring how this will add to our understanding of brain injuries, how the brain ages and neurodegenerative disease.
New Zealand is at the forefront of these global breakthroughs in brain science. “There’s a lot of interest in how the brain moves and it’s definitely an area where we have a lot of expertise,” says Samantha Holdsworth, research director of the Mātai Medical Research Institute in Gisborne.
With a traditional MRI it is crucial to remain very still to prevent the image blurring. This new method of tracking micromovements was developed by Holdsworth and her team during an 11-year stint at Stanford University’s radiological research centre.
They took an algorithm originally developed to amplify videos and tailored it for MRI, creating a revolutionary and non-invasive way of examining in real time what the brain is doing and how it moves.
“We’ve been able to amplify the motion of the brain about 50 times,” says the medical physicist. “The most it moves is around 1.4mm.”
There are already signs this will advance our understanding of brain diseases, including dementia. An international team of scientists has used the new amplified scanning technique to discover that the brains of dementia patients seem to move differently, and there is hope this has the potential to provide an early warning of neurodegeneration.
Meanwhile, researchers at Mātai have been looking at how the brain moves during exercise. They’ve learnt so far that during rest, the brain’s rhythmic motion matches the heartbeat. However, even light exercise that lifts the heart rate, such as squeezing a hand grip, alters blood flow and increases cerebrospinal fluid movement, making the brain more stable.
“This suggests regular movement or exercise may play a vital role in regulating brain fluid to keep the brain balanced and healthy,” says Eryn Kwon, a senior researcher at Mātai. It’s already well known that regular physical activity can reduce the risk of developing dementia and the way exercise affects brain dynamics may be playing a part in that –something researchers are keen to explore further.
Another application for this exciting technology is to improve treatment for a brain condition called Chiari malformation. Believed to affect about 1 in 1000 people, in a Chiari malformation part of the brain tissue pushes down through an opening at the base of the skull and into the spinal canal.
Many with the condition have no symptoms and require no treatment, but for some it can lead to a range of problems including headaches and unsteadiness. The most severe form brings a higher rate of death.
Amplified MRI techniques have shown that with a Chiari malformation the brain can have an abnormal movement, and Holdsworth says amplified MRI may better guide treatment, identifying which patients need invasive brain surgery.
“The early data we’ve got on Chiari is looking promising, with a study showing brain motion can predict outcomes in surgery,” she says.
In a further groundbreaking project, amplified MRI has been combined with other types of imaging to measure and predict brain pressure non-invasively. Raised pressure around the brain (intracranial hypertension) has many causes but for some people there is no obvious reason and they may need surgery to insert a shunt to drain fluid.
Hydrocephalus, which involves an abnormal build-up of cerebrospinal fluid inside the skull, also causes pressure on the brain and can damage tissue.
The new methods and tools researchers are developing aim to identify these disorders earlier and improve outcomes.
Last year, Holdsworth was co-chair of the first interdisciplinary Royal Society pulsing brain meeting, held in the UK. And five papers involving Mātai and New Zealand researchers have recently been published in journals of the UK Royal Society. “We’re adding another dimension to understanding brain health,” she says. “This progress opens new possibilities for diagnosis and treating brain conditions using motion-based biomarkers.”
