What happens when man merges with machine? Society has already toyed with this concept with pop culture characters like Marvel hero Iron Man and movies like Pacific Rim. Artificial but ‘intelligent’ prosthetic limbs that learns a user’s gait enables amputees to regain near-normal functions have already been invented1. Cue neuroprosthetics – the vanguard of medical technology. This article aims to explore the concept of neuroprosthetics and its ability to change the practice of medicine.

Devices that link machines directly to brains

Neuroprosthetic devices take prostheses one step higher by linking them directly to the brain. They aim to augment or bypass damaged nervous system pathways. Neuroprosthetic devices have been designed to function in both directions – either by translating sensory information to the brain, or by decoding brain activity into motor movement.

The cochlear implant, a device that most physicians may be familiar with, is in fact the oldest type of sensory neuroprosthetic. First created in 1957, this implant translates sound from the environment and directly stimulates the auditory nerve – bypassing severely damaged sections of the ear.

Patients can see again after receiving artificial retinas

Today, scientists have succeeded in creating a neuroprosthetic for vision – the artificial retina3. The world’s first artificial retina, the Argus II, gained US Food and Drug Administration (FDA) approval in 2013. It works by using a small camera attached to glasses to send information from the surroundings to a small device implanted on the retina2.

Argus II helps improve orientation and mobility… It allows you to see sidewalks, to determine where you are and perform simple chores like sorting laundry,” explains Mark S. Humayun, creator of the Argus II. The innovative creation is currently only indicated for those with retinitis pigmentosa and is only able to restore low resolution vision4.

In the short four years since then, scientists have been working hard to develop better and clearer artificial retinas. The latest is the development of a thin conductive polymer embedded on silk, created by scientists from the Italian Institute of Technology. This implant has already been proven successful in rats, and the team hopes to bring their creation to clinical trials soon5.

"We plan to carry out the first human trials in the second half of this year and gather preliminary results during 2018. This implant could be a turning point in the treatment of extremely debilitating retinal diseases," comments ophthalmologist Grazia Pertile, a researcher working on the project5.

Neuroprosthetics can accelerate recovery from paralysis

The dreaded diagnosis of paralysis strikes fear in anybody’s heart. There is only so much that rehabilitation can offer for patients with severe neurological damage caused by spinal cord injuries, strokes and degenerative diseases such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS).

Neuroprosthetics have been designed to restore partial and sometimes full body mobility in paralysed patients. Paralysis often occurs due to localised damage to one section of neurons, leaving other parts of the motor pathway intact. These devices work by connecting healthy motor brain areas directly to the peripheral nervous pathways and the limbs, bypassing the damaged neurons6.

A major challenge in developing neuroprosthetics lies in decoding brain signals. Methods that scientists have explored include using electroencephalographs (EEGs – measures brainwaves on skull surface), electrocorticography (ECoG - measure brainwaves on the surface of the cortex) and implanting electrodes directly into the brain, where they can transmit electrical impulses7.

Scientists have already succeeded in using this technology to rescue a victim of ALS that was suffering from locked-in syndrome. Early this year, Bill Kochevar, a 53-year-old paralysed man was been able to drink and feed himself for the first time after eight years. Bill was fitted with a system that connected electrodes in his motor cortex to sensors in his forearm.

“I think about what I want to do and the system does it for me… when I want to do something, my brain does what it does8,” says Bill.

“With further development, we believe the technology could give more accurate control, allowing a wider range of actions, which could begin to transform the lives of people living with paralysis,” says Dr Bolu Ajiboye, lead author of the team that helped Bill regain function8.

Permanent neurological damage may no longer be permanent with neuroprosthesis

The field of neuroprosthetics is still in its infancy, with patients experiencing some recovery of function rather than total recovery of function. However, these seemingly small improvements are gigantic for those who have been completely immobile. Scientists are optimistic as these successes have confirmed that the concept is viable and are working towards refining the devices.

With the burgeoning growth of medical technology, physicians can expect to see a larger proportion of patients with some form of prosthesis. Will maintenance of these prosthetics be part and parcel of regular medical practice in the future? Only time can tell. MIMS

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Sources:
1. https://singularityhub.com/2009/08/27/bionic-limbs-with-artificial-intelligence/
2. http://sitn.hms.harvard.edu/flash/2013/issue138a/
3. https://www.osa-opn.org/home/articles/volume_28/april_2017/features/vision_accomplished_the_bionic_eye/
4. https://www.asrs.org/retina-times/details/131/fda-approves-world-first-artificial-retina
5. https://www.sciencealert.com/scientists-have-created-an-artificial-retina-implant-that-could-restore-vision-to-millions
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3118434/
7. http://www.the-scientist.com/?articles.view/articleNo/41324/title/Neuroprosthetics/
8. https://www.theguardian.com/science/2017/mar/28/neuroprosthetic-tetraplegic-man-control-hand-with-thought-bill-kochevar