Paralysed patients could benefit from robotic aids

Published: June 18, 2010  |  Source: theengineer.co.uk
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Patients with spinal cord injuries could one day move paralysed parts of their bodies with a wearable robotic device controlled by a wireless chip implanted in the brain.

The technology is being developed through a £1m government-sponsored research programme involving academics from Leicester University, Newcastle University and Imperial College London.

Rodrigo Quian Quiroga, the principal investigator of the Leicester University group, said that the challenge will be to develop a tiny chip packed with hundreds of electrodes for recording neuron activity in the brain plus data processing capabilities and a wireless transmitter for sending signals outside a patient’s skull.

The battery-powered chip would, essentially, decode a person’s thoughts, which are represented in the brain as a pattern of neuron activity. As Quian Quiroga explained, a patient with a spinal cord injury may lose the ability to move his or her arm, for example, but there is nothing wrong with the person’s brain.

‘The guy can see the object he wants to reach, the guy can have the intention to reach to the object, the brain can send a command to the arm – “Reach for this cup of tea” – but the signal gets broken at the level of the spinal cord,’ he said.

‘If we can get the signals from these neurons and interpret them with what is called decoding algorithms, then we can move a robot device placed on the paralysed arm,’ added Quian Quiroga.

It sounds far fetched, but, according to Quian Quiroga, the technology to do this is already available. Research groups around the world have demonstrated these sorts of implantable chips in the brains of monkeys, he said. The difference is that the information is not wirelessly transmitted outside the skull. Instead, the chip is attached to a cable, which sticks out of a hole drilled through the skull.

Quian Quiroga said: ‘It’s not just an aesthetical issue; it’s also a hygienic issue because if you have a cable, this means you have a hole in the skull and this means you have more risk for infection.’

The bottleneck for researchers seeking to go wireless has been bandwidth and transmission. Just sending a signal from one electrode wirelessly requires transmitting 30,000 data points per second.

Quian Quiroga added that the problem is multiplied further when data points need to be sent from hundreds of electrodes.

‘It’s a huge amount of data so the bandwidth won’t be enough,’ he said. ‘We’re trying to do some basic processing on the chip to reduce the bandwidth. So instead of 30,000 data points per second, maybe we’ll be sending 100 data points per second or 1,000.’

Dr Andrew Jackson, the principal investigator of the Newcastle University group, said there could be other applications for their chip implant and envisioned a possibility where a robotic device would not even be necessary to move paralysed parts of the body.

He suggested an idea that would artificially replace the damaged connection between the motor cortex, which is the area of the brain that controls movement, and motor neurons in the spinal cord. The chip would collect neuron activity in the motor cortex, process the data and send signals either through wires under the skin or short range wireless transmission to an implantedstimulator in the spinal cord. This stimulator would be directed to generate electrical impulses to move paralysed limbs.

Dr Jackson said the concept is similar to deep brain stimulation, which has proven to have therapeutic benefits for patient’s suffering from conditions such as Parkinson’s disease.

It could be a long while before electrical stimulation is used in spinal cord injuries, but Quian Quiroga sees the idea of a brain implant controlling an external robotic device as a potential solution in the near future. With successful animal trials, he said the technology could be used to benefit patients within five years.