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Andrew Jackson: Listening to brain cells

Andrew Jackson is a Wellcome Trust Research Career Development Fellow in the Newcastle University Institute of Neuroscience. He told Katherine Nightingale about research, part-funded by the MRC, which aims to decipher the brain patterns that control arm and hand function to help paralysed people.

Like many researchers who run their own lab, Andrew Jackson doesn’t spend as much time at the bench as he’d like. But he does get to spend the odd hour or two doing one of his favourite things — listening to brain cells.

“They become like old friends,” he says. “We’ve been able to track the same neuron over days, weeks and months and you start to get to know them quite well.”

There are important reasons for getting to know neurons. Andrew and his colleagues are hoping to use the knowledge they gain from listening in on the brain to allow paralysed people to control external devices such as prosthetic arms using just their thoughts.

“The brain is a very democratic organ — the movements you make are determined by the activity of a large population of neurons, communicating with each other by sending small pulses of electricity. By ‘listening’ to these pulses using electrodes (fine wires inserted into the brain) and identifying patterns in them, we can understand how these control movement,” says Andrew.

A person paralysed by an injury to the spinal cord still has functioning brain cells that control movement. So when they think about moving their arm, the same brain cells that would function in a non-paralysed person are active. An electrode implanted in the brain can detect this specific signal, decode it, and transmit it to the device.

Work in the United States has shown that a small number of people have used this technique to high-five their girlfriend, for example, or drink from a bottle.

But Andrew’s ultimate aim is to restore people’s use of their own limbs. Rather than the signal going to an external device, it would be sent to an electrode in the spinal cord, circumventing the spinal injury.

“This means we would bridge the injury and restore the pathway from the brain to the muscles. This is what patients would like — to be able to move their own limbs again.”

Primate pathways

Though the techniques using external devices have been tested in people, it would be unethical to carry out large-scale trials at the moment, says Andrew. The only type of electrode that has been approved for use in humans doesn’t always read and transmit signals effectively, for example.

Andrew is looking into improving the electrodes themselves and how to use them to get reliable signals from the brain. To do this he uses macaque monkeys.

“We need to see whether we can develop better electrodes, better techniques for using those electrodes and better ways of putting the whole system together. These are experiments that can only be done in monkeys at the moment.”

Macaques and humans share a pathway — unique to primates — via which signals from the brain control the arm and hand. Mice and rats, which use all four limbs for walking, don’t share this pathway.

Andrew is perfecting techniques to identify patterns in brain activity using electrodes. To do this, he and his team listen in to the macaques’ brains while they are performing tasks such as moving a coloured spot onto a target on a computer screen. At first, they do this using their hands, and eventually learn how to control the coloured dots with their minds.

Some macaques are more suited to doing these kinds of tasks than others, and Andrew is exploring ways of determining this early on. He has been funded by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) to develop a way of identifying the macaques with an aptitude for training while they are still at the MRC Centre for Macaques, the breeding centre from which all macaques used for academic research in the UK must come.

“We’re hoping to start training at the breeding centre, to see which animals most like to play these games and might be best suited to a laboratory environment. This improves the welfare of the animals but also the science, meaning we’ll use fewer animals in the long run.”

Andrew also needs macaques for his efforts to give paralysed people back the use of their own arms. His team have shown that a macaque with a temporarily paralysed hand can reach and grasp for objects when signals from its brain are routed to electrodes in its spinal cord, giving hope that the same could be done in people.

The mystery of the brain

Andrew did an undergraduate degree in physics, but struggled to find an area of research in the field that felt mysterious enough. “The problem with physics is that we understand a lot about it — you have to start building particle accelerators to find something physics doesn’t understand. The brain weighs about a kilogram, we’ve all got one and yet we understand little about how it works. To me that’s always been fascinating.”

He found a neuroscience PhD programme at University College London that allowed him to complete three separate research projects in the first year, including one on the motor system in non-human primates. “I found it amazing that you could listen to the signal from a brain cell while seeing an animal performing an action — it was a vivid demonstration of what we know but is sometimes hard to believe.”

Four years as a postdoc in Seattle piqued Andrew’s interest technologies to help paralysed people. There he developed the technology that allows him to record brain signals in macaques which he still uses today.

Does he think his beginning in physics has helped him in modern neuroscience? “Definitely. Neuroscience is becoming more mathematical —it’s one thing picking up anatomy and learning names for parts of the brain, but I’m pleased I did all the mathematical training when I was younger!”

Katherine Nightingale

Here’s a video featuring Andrew talking about his research using macaques.

[Video link for access.]

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