Melbourne researchers bridging the gap between machine and brain

Melbourne’s world-leading medical technology sector is breaking new ground in the treatment of paralysis through the development of a tiny, biocompatible device that harnesses the power of the mind.

A team of Melbourne medical researchers are preparing to conduct human trials of a breakthrough medical device that promises to get paralysed people back on their feet.

Their tiny invention is no bigger than a paper clip, but its potential to revolutionise the treatment of the disabled has attracted millions of dollars in funding from a number of sources including DARPA, the US Department of Defense’s research unit, and Australia’s National Health and Medical Research Council.

The ‘stentrode’ is a slender, cigar-shaped bundle of fine wires and electrodes. It is designed to be implanted, using a catheter fed up through the groin, into a blood vessel near the motor cortex, that part of the brain which controls movement.

From here, it passively records the activity of tens of thousands of brain neurons. This information is then transmitted via delicate wires that run from the head, through the neck to a transceiver in the patient’s chest.

Using a complex set of algorithms, this data is translated into commands to control a mechanical exoskeleton or bionic limb.

In early 2018, the first stentrodes used in humans will be implanted into a small group of paraplegic or quadriplegic patients by surgeons at the Royal Melbourne Hospital. The first patients will most likely be young people who have suffered a traumatic spinal cord injury around six months to a year earlier.

The work is the result of close collaboration between the University of Melbourne, the Royal Melbourne Hospital and the Florey Institute of Neuroscience and Mental Health.

The project’s chief engineer is Dr Nick Opie, a senior research fellow at Melbourne University and co-head of the Vascular Bionics Laboratory at the Royal Melbourne Hospital.

He says the concept has been proven in humans before, but only by using invasive methods that have several major disadvantages to the stentrode.

Opening the skull and implanting electrodes into the brain is dangerous, with very high rates of infection and bleeding.

“The main benefit of our technology is that it is housed within the blood vessel,’’ says Dr Opie.

“Epidural arrays penetrate the brain, which is risky. And experience has shown that they get rejected and stop working over time.’’

Although the stentrode never touches the brain, animal trials have shown that it is capable of transmitting just as much information as invasive electrodes.

The first human stentrode users will start slowly, using simple tasks to train both their brains and the software that translates their thoughts into machine commands.

Decoding the brain’s activity is not a simple task, and the team are still refining the algorithms they will use to drive the robotic extensions.

“The maths is a very large party of this,’’ says Dr Opie.

“Our patients will first learn to control a simple 2D device such as a mouse, then go to something more challenging such as a 3D game, before they go on to control a motorised wheelchair or exoskeleton.

“We know from trials with invasive devices that over time the use of these devices eventually becomes easy as controlling one’s own limb, without having to think about it.’’

Dr Opie says the team still face numerous hurdles before the stentrode becomes commercially available, but he relished the challenges the project throws up.

“I’ve always been fascinated by the integration of man and machine, and the ways that people and machines could function together,’’ he says. “Fortunately, I was born in the time to do this.”