Not many PhD students prepare for a game-changing neuroscience experiment by practising ping-pong on a beach in Spain. But Elena Boto’s ability to keep a table tennis ball up in the air was a novel way of trialling a device set to transform brain imaging.
Back in Nottingham, Elena showed off her skills to colleagues at the Sir Peter Mansfield Imaging Centre. She’d swapped a sunhat for a revolutionary brain scanner, worn like a helmet and capable of measuring neurological activity in ways never captured before.
Unlike a traditional MEG (magnetoencephalography) scanner, inside which subjects must sit or lie, the lightweight MEG system worn by Elena allowed her to move naturally – nod, stretch, drink a cup of tea …and even play ping-pong.
Dr Matt Brookes, with the centre’s director, Professor Richard Bowtell, led the Nottingham team behind the wearable prototype. “There were about 10 of us there with Elena,” Dr Brookes recalls. “Afterwards we looked at the results – ‘wow’! The quality of the data showed that the scanner worked even better than we’d hoped.”
In a few more years, thanks to virtual reality, we could be imaging brain function while people do, quite literally, anything.
Currently, MEG scanners weigh around half-a-tonne as they house sensors kept at -269°C. Subjects must keep still as even a 5mm movement can ruin images of brain activity. It’s ill-suited to anyone who finds it difficult to keep still, such as children, infants or patients with movement disorders. And because keeping still inside a big machine isn’t very stimulating, they can only reflect a limited range of brain activity.
Now the ability to capture data from moving subjects and the sophisticated brain signalling required to keep a ping-pong ball in the air suggests exciting potential applications.
Brain events such as an epileptic seizure could be captured and movement disorders such as Parkinson’s disease studied in new detail, while young patients can have a brain scan even if unable to keep still. The system also offers a potential step change in precision medicine, by supporting better targeting, diagnosis and treatment of mental health and neurological conditions.
The wearable MEG system would also capture the brain’s reactions to wider ranges of social, environmental and physical inputs.
“In a few more years, thanks to virtual reality, we could be imaging brain function while people do, quite literally, anything,” said Dr Brookes.
The project has its roots in a long-standing partnership between physicists at Nottingham and the Wellcome Centre for Human Neuroimaging, University College London.
They realised a new generation of quantum sensors, which are lightweight and operate at room temperature, could allow smaller-scale MEG technology, while increasing its sensitivity if sensors were much closer to the brain.
“Gareth Barnes [of the UCL centre] and I asked ourselves,” said Dr Brookes, “now we can move the sensors close to the brain, can we design a scanner that’s wearable?”
Five-year funding from Wellcome led to a wearable scanner that allowed sensors to align with areas of the brain. This precision offers the possibility of capturing brain signals with four-fold sensitivity in adults and 15 to 20-fold in infants.
The helmet was created as an exact fit for Elena Boto, following 3D-mapping of her head. She initially waggled a finger, before the researchers incrementally set her new tasks to test the sensitivity of the helmet.
It was UCL’s Professor Gareth Barnes who playfully suggested that Elena take up ping-pong. “It was good fun, and really, really exciting because we were getting stunning results,” said Elena, who is cited as the joint lead author, with fellow PhD students Niall Holmes and Gillian Roberts, and Research Fellow Dr James Leggett in the team’s Nature paper, Moving magnetoencephalography towards real-world applications with a wearable system.
For Dr Brookes, the next steps are designing a bike helmet-sized scanner, offering more freedom of movement and a generic fit so the technology can be more widely applied. “We’re talking to people at Great Ormond Street Hospital and hope to use this technology to help find treatments for children with epilepsy.”
Professor Barnes added: “This has the potential to revolutionise the brain imaging field, while transforming the scientific and clinical questions that can be addressed with human brain imaging.”
Maths, masking tape and electromagnetic coils
To make the wearable MEG system viable, the Earth’s magnetic field had to be reduced around the sensors. PhD student Niall Holmes, working with Professor Richard Bowtell, Director of the Sir Peter Mansfield Imaging Centre, found a solution.
For the wearable MEG scanner’s quantum sensors to operate, it can only be operated inside a Magnetically Shielded Room, which is formed of special metal alloys that prevent the Earth’s magnetic field from entering it.
Niall explained: “The bulk of the work at reducing the magnetic field is done by the room but some field remains. For conventional MEG this is fine but with the new technology we need the background field to be exactly zero.”
Dr Matt Brookes turned to Professor Bowtell, a long-time collaborator of Noble laureate Sir Peter Mansfield, who suggested a system of electromagnetic coils to reduce the effect of the Earth’s magnetism. Niall set about designing the coils, which sit in looping patterns on movable wooden, whitewashed boards around the subject, but no so close that they restrict movement or feel claustrophobic.
Niall, a second-year doctoral student, said: “The shielded room reduces the Earth’s magnetic field by a factor of around 50,000. The coils provide additional shielding, by a further factor of 15, but also make the remaining field spatially smooth. It is the spatial smoothness of the field that really allows the subject to make large movements.”
He said of the project: “It’s been amazing. There’s a lot of computation and maths going into the design, and of course the brain imaging work, plus engineering, too. It’s very complex but there’s also been a lot of masking tape.”
Meanwhile fellow Physics PhD student Gillian Roberts was addressing another challenge, precisely measuring the movement of the helmet worn by Elena Boto to better correlate with data from her brain activity as she moved a finger, drank tea...or played ping-pong.
An old motion-sensing Xbox Kinect helped inspire Gillian to devise a 3D imaging system to track the helmet’s movement.
Now Niall is designing new coils for a lab at University College London to support work with epilepsy patients at nearby Great Ormond Street hospital, whereas Gillian is investigating how virtual reality software could eventually be combined with the wearable MEG scanner to give patients a truly immersive experience.
Both PhD students are among the authors cited in the paper published by Nature. Dr Brookes is delighted that the project draws in a team at the Sir Peter Mansfield Imaging Centre ranging from its Director, to post-docs, PhDs and undergraduates (Izzy Gale and Maddie Wyburd used optical performance monitoring to measure muscle activity).
Dr Brookes said: “Our undergraduates should be excited about physics research, and they are. There’s often a perception that academics only really care about their research and that teaching is something that they do on the side. It’s not true – one informs the other. It lets students see the real benefit of coming to a leading research university and using world-class kit.”