Dr Eric C Leuthardt, 45, is a neurosurgeon at Washington University in St Louis. He is also the co-founder of NeuroLutions, a research laboratory developing direct interfaces between mind and computer. Leuthardt is pioneering the use of electrical brain implants to help restore motor function to the paralysed limbs of stroke victims. He is also helping to develop electrode systems that can directly decode the unspoken “inner voice” of the mind, and use it to direct external action; for example, Leuthardt’s subjects have been able to control the cursor of a Space Invaders video game just by thinking. He has published two science fiction novels aimed at “preparing society for the changes” that his work predicts. He believes that in the coming years neural implants that link the human brain directly to computers to enhance cognitive functions will be like pacemakers or tattoos, used with hardly a second thought. This interview was conducted by phone, when Leuthardt had just dropped off his children at school and was on his way to perform an operation to remove a brain tumour.

A direct neural interface with machines has long been a science fiction dream. When did you first get involved in helping to make it happen?

I started down this road back in 2002, when people were testing the first examples on monkeys. We have come a long way since then. We have a number of different implants being used in clinical trials now. In my view, we will reach a real inflection when these things become really clinically relevant.

How far along that route are you?

We have finished our first successful clinical trial with stroke patients. In the near term we will be in discussions with the US Food and Drug Administration to bring this technology to wide clinical use, which will hopefully happen in the next couple of years.

I now see companies emerging actually promising to do what I wrote about in fiction Eric Leuthardt

I guess any procedure involving the brain feels like a different category of risk to most people. You must face that anxiety every day.

I think there are two types of surgical practice that really strike at the core of people’s anxiety. One is brain surgery, where you are operating on something that people see as themselves, their sense of identity, their mind. The other one is, I think, paediatric surgery, where the operation is on the thing most precious to you – your children. I think both create a dynamic where you need to work harder to create trust with your patients.

When it comes to innovation that might link a person’s mind directly with a machine, it seems as much an ethical as a medical question. Is that how you see it?

Ethicists are critical in what we do. A working interface would be a real turning point in human evolution. I don’t say that with bombast or hyperbole. And just like with artificial intelligence, we need to take the greatest care in how we think about it. Whether it happens in five years or 50 years, it will happen. I wrote these two science-fiction novels to try to walk people through some of the things that could happen; for example, if others got unauthorised access to these implants, or when corporations got involved. We need to be thinking about these things now, rather than after the fact.

Was one of the motivations in writing your books to work out these things for yourself? Did you feel the same at the beginning of the process as at the end?

I had certain ideas in mind when I started the books, but there was an evolution. I came to think less about that individual interface and more about the effect this technology might have on society. We need to think hard about how advances [might] not increase social division.

You are an optimist, but presumably it’s a guarded optimism?

I’d like to think it is an informed optimism. Human intelligence is the most important resource on the planet, to preserve ourselves and the world. I believe the more we can advance human intelligence the better equipped we will be to do that. But we are in explosive times. Some of the fiction that I wrote even a few years ago I now see companies actually promising to do [what I described]. The premise of my second book was a neural implant that would allow you to download all your thoughts and create a virtual version of yourself. I saw the other day a company selling something that offers a scan of your brain and creates a virtual version, which is getting pretty close.

The billionaires of Silicon Valley, the pharaohs of our age, intent on immortality, seem particularly interested in the technology. Elon Musk, Mark Zuckerberg, the founders of Google are all developing projects in this area. What will be the next big advance?

Capturing the mechanical intent of imagined words is not that hard with this technology. I and a number of others have shown it is at least possible. What is much harder is higher-level semantics – capturing ideas directly from the brain. But I think we will get there.

Decoding that inner voice seems one step closer to understanding the ultimate mystery of consciousness…

It starts to challenge some of our fundamental assumptions of the mind/brain relationship. We always had this idea that the software is separate from the hardware… we are now showing that the software is represented in the hardware.

I understand you studied theology as an undergraduate. Does that inform your work at all?

I got a degree in biology and theology. I was interested in bringing very different disciplines together. One of the things I have always said is that in many ways theology was more important. It forced me to think about the big picture and to write my thoughts down. I think that has made me both more analytic in my science and more inductive in where that can go. Theology helps you realise how faith is an embedded part of our psychology – leaving aside religion, scientists have all sorts of beliefs they hold on to which the data does not support. Scientific advance is often as dependent on conversion, just as much as any religion.

As a surgeon, when you are faced with a brain very directly, do you have a very clear sense of the person, the thing you are trying to preserve?

Absolutely. There is a duality to it. One is the utter respect it demands. The other is how we are now seeing how the brain is much more plastic than we thought. The ability to recover function is extraordinary.

We have always had a sense that it doesn’t heal…

That’s right. If we take some of it away we tend to think there is no way our mind will return to “normal”. In fact, experience often shows the opposite.

I wrote recently about the “biohacking” movement – people who attempt DIY implants to enhance their cognitive functions. Do you have such people volunteering to be part of neurointerface trials?

Somebody called my secretary yesterday, saying they wanted an implant to meld themselves with artificial intelligence, and might I be someone who could help them do that? There is definitely an interest.

When I give talks, I ask the question: “If I offered you a small surgery, a one-centimetre incision, and I told you I could improve your memory by 50%, who would want one?” In the younger generation almost all the hands go up. Clearly this notion of altering yourself has changed dramatically. No one had tattoos 30 years ago, now more than 50% do.

Would it be something you would welcome yourself?

Yes. I had one of my engineers build a non-invasive brain stimulator for myself, and I used it when I was writing my second novel. It clearly made a difference. I did a little experiment. I found I could write 500 words in 30 minutes, where it used to take me an hour or more …

Where do I get one …?

Other scientists who ventured into sci-fi

Fred Hoyle

As well as formulating the theory of stellar nucleosynthesis, the Cambridge astronomer wrote numerous science fiction novels, including A for Andromeda which was turned into a BBC TV series in 1961 and later remade as a film with Kelly Reilly and Tom Hardy.

Norbert Wiener

The great US mathematician, credited as the father of cybernetics, wrote a 1959 novel called The Tempter, exploring the moral quandaries that arise when the worlds of science, engineering and business collide.

Julian Huxley

The British evolutionary biologist, brother of Aldous, made one notable foray into fiction. His 1926 story The Tissue-Culture King tells of a biologist captured by an African tribe who ingratiates himself by culturing the living tissue of their king.

Leo Szilard

In his 1948 short story, Report on “Grand Central Terminal”, the Hungarian-born physicist – who developed the idea of the nuclear chain reaction and later cautioned against nuclear weapons – imagines aliens visiting our post-apocalyptic world and trying to figure out what wiped out life on Earth. Killian Fox