Beyond human: neuroengineering healthier lives

Neuroengineering offers us a chance to alleviate the pain of the 1 billion people worldwide who suffer from neurological and psychiatric disorders.

neuroengineering

The ability to seamlessly blend man and machine may sound like the preserve of science fiction novels. Yet technologies that can harness the electrical properties of the human brain might soon turn those futurist visions into reality.

Neuroengineering, the term given to a group of pioneering techniques that blend neuroscience – the analysis of how a brain’s neurons work to generate a person’s thoughts and actions – and electronic engineering, or the application of physical laws, is advancing at a rapid rate.

Neuroengineers have essentially evolved into the electricians of the human brain and nervous system, troubleshooting and rewiring the circuitry to identify and fix impairments or hooking up electronic devices like prostheses to enhance function.

Their expertise is already helping improve the well-being of patients with motor disorders.

parkinson

The origins of neuroengineering can be traced back to the 1980s, when detailed studies of the inner ear led to the development of cochlear implants, devices that have since brought sound back into the lives of more than 300,000 people who were previously hard-of-hearing.

A decade later saw the emergence of deep brain stimulation (DBS), a technique which, although still not fully understood, has benefited more than 100,000 people with Parkinson’s disease, dystonia, essential tremor, and even Tourette’s syndrome and obsessive-compulsive disorder.

In DBS, electrodes are implanted in the brain and attached under the skin to a pacemaker-like device called a neurostimulator, which is fitted below the collar bone. The system then electrically stimulates specific brain areas to block abnormal nerve signals.

Now, neuroengineering appears to be entering a new era of innovation.

The latest development to capture the imagination of medical practitioners is the bionic eye. Although only a few retinal implants are on the market, US-based Second Sight has implanted at least 150 of its USD150,000 Argus II systems into the eyes of poor-sighted people around world.

eye

The outside of the system consists of a small camera set in a chunky pair of sunglasses attached to a handheld computer. Image data is then transmitted wirelessly to an implanted microelectrode array on the patient’s retina. After learning to interpret the new signals, patients report the ability to read large-print books, cross the street on their own and even see images of their relatives.

Also starting to see the benefits of neuroengineering advances are people with neurologic disorders, which affect sufferers’ ability to move part (or all) of their body. These illnesses include amyotrophic lateral sclerosis, stroke-induced locked-in syndromes and spinal cord injury.

Because both physical and imagined actions trigger similar levels of brain activity, patients taking part in experimental brain-computer interface studies need to simply think about a command to execute it.

Alzheimer

The process works in the following way. A patient imagines moving an arm. The physical manifestation of that thought – an electrical impulse – flows from the brain to the sensors implanted either within or outside the cortex. The sensors then translate those signals into computer code, which is fed into a mechanised robotic arm. The arm is then raised.

Interventions such as these have allowed patients that have been paralysed by severe motor disorders to communicate with the outside world.

The scope of neuroengineering goes beyond physical functions. Researchers believe it could ultimately lead to the reversal of memory loss in conditions such as Alzheimer’s disease (AD).

Dheeraj Roy, a neuroscientist at the Massachusetts Institute of Technology, is studying memory loss in mice that have AD.

Publishing the results of his analysis in the journal Nature last year, Roy revealed that the application of neuroengineering techniques enabled some of the animals to partially recover their lost memories.

Neuroengineering could ultimately lead to the reversal of memory loss in conditions such as Alzheimer’s disease.

“Using mouse models of early AD, we were able to stimulate memory engram cells that were formed the previous day when the animal learned that ‘this environment is scary’ and we got the mice to recall this supposedly lost memory,” he explains.

As things stand, the technique he and his team used (known as optogenetics) could never be applied to humans. That is because optogenetics requires us to artificially introduce a light-sensitive protein into brain cells using a virus. “The viral infection step and the need for highly invasive implants are major barriers to translating this approach directly to patients,” Roy observes.

Yet he remains optimistic that their breakthrough will lead to new AD research and eventually treatments: “We hope that scientists will develop more translatable techniques in the near future.”

alzheimer projection
  1. Prof. Silvestro Micera - "We want to do it the right way"

    hearing aid
    bionic hand

     

    Silvestro Micera from École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland conducts research at the cutting edge of translational neuroengineering. Here, he offers an insight into how he hopes to improve the lives of amputees by developing bionic arms.

    Why should we take notice of neuroprosthetics now?

    This is a very important time for neuroprosthetics. Already we have cochlear implants, deep brain stimulation and visual prostheses for sight restoration – so there are quite a lot of clinically important and valuable solutions out there. But in the next 10 years more patients will benefit from this type of technology.

    You became famous in 2014 for restoring a sense of touch for amputee Dennis Aabo Sørensen with a ‘feeling’ hand. How is Dennis getting on with the device?

    Our next step was to show that it was possible to provide information about the texture of different samples or objects that he touched through implanted electrodes in his upper arm.

    Unfortunately, we had to remove the electrodes at the end of the experiments, but we are grateful because he helped us understand what we can do in terms of long-term computer implantable devices that will really help patients.

    Why is sensory information so important for Dennis and other prosthesis users?

    If you look at surveys of amputees, they all say that the main issue is the lack of sensory information. The more you are able to provide natural or quasi-natural information, the happier the user will be to use the prosthesis and the more the patient will be able to feel the prosthesis as part of his or her own body.

    What is next for your neuroprostheses?

    The next step is to develop a long-term implant, which means not just for four weeks as we did with Dennis, but for months and eventually years. We have started looking at robotics for neurorehabilitation after stroke, and we are also working on controlling spinal cord stimulation to restore locomotion in people with paraplegia.

    What is the main barrier to clinical adoption of your technologies?

    It’s really a huge effort in terms of time and money because, of course, at the end what you are doing is making something for patients who, by definition, are extremely fragile.

    It’s a bit frustrating that it takes so much time sometimes, but it makes sense because we want to do it in the right way.