15 Oct 2016

Restoring touch to paralysed patients

From This Way Up, 12:50 pm on 15 October 2016

An electronic brain implant has allowed a spinal injury patient to feel sensations in his hand for the first time in a decade.

Scientists have made important advances in this area in recent years, Dr Smith tells Simon Morton, but so far these have centred on translating neurological activity using implants in the brain's brain's movement centres into movements of prosthetic limbs or robotic devices. 

"In all these cases, although a patient can make something move, he or she still lacks a sense of touch [which makes] manipulating objects with a prosthesis very difficult because it is hard to judge how much force is being applied."

Now neuroscientist Robert Gaunt and his colleagues at the University of Pittsburgh, writing in the journal Science Translational Medicine have used a network of tiny implantable electrodes in the brain's somatosensory cortex (a sensory area in the front part of the brain) that use small electrical currents to stimulate underlying nerve cells to fire impulses that the brain interprets as a sensory experience.

"This patient has not felt anything from this part of his body for ten years. But the signals we supplied produced sensations that felt normal to the subject. That shows that the underlying wiring in the brain is still intact" - Robert Gaunt.

"The patient was able to 'feel' sensations that appeared to be coming from his hand. He described the sensations as feeling like 'pressure', or tapping, buzzing or 'electricity'. And by stimulating different parts of the electrode array, it was possible to elicit sensations in different parts of the patient's hand" says Dr Smith.

He said the challenges now facing the team are extending the electrode network to cover more of the body and discovering how to make the sensations more meaningful to the patient.

An MRI scan is used to target the right location to implant the device.

An MRI scan is used to target the right location to implant the device. Photo: Handout / CALTECH / AFP