Brain-computer interface is... just what it sounds like. Some device is used to transfer information about the brain's activity to a computer, or vice versa. So we end up with two flavors of BCI: recording (for the brain-to-computer direction), and stimulating (for the computer-to-brain path). Utilizing the lucky fact that electrical signals are the language of the brain, we can do both of these things with tiny electrodes placed either in, on, or next to cells. And with this dual pathway we can then read off motor cortex information in order to move a prosthetic limb, or send seizure-combating signals into an epileptic brain. It seems so simple, right?
But, like the Texas penal system,what we've got is an execution problem. There is no easy way to get those electrodes to the cells. And once they're in, there are still risks of infection or rejection. The signal is also subject to degradation by movement, electrical noise, or electrode deterioration. These are problems routinely faced by researchers working with animals, and are only magnified tenfold when the possibility of human applications arises. Right now, non-invasive techniques such as EEG and fMRI are the most common methods of reading brain activity in humans. But none of those options have the spatial or temporal resolution to provide meaningful data about real-time information processing, which is critical for the goals of any BCI. For useful data, we need those tiny electrodes. But as long as implanting them remains such an invasive, messy, and potential dangerous procedure, it won't be available to the masses.
Now, it should be noted, there is the minor matter of knowing what those neural signals that we record actually mean. Or figuring out how to make a pattern of stimulation that has the intended effect. Cracking the neural code is obviously key to interfacing with the brain; it's hard to have a conversation when you don't speak the language. And right now we are far from fluent. But it is an area of huge research and I believe the breakthroughs are coming. However without the ability to utilize that knowledge in a physically plausible way, we don't stand much to gain from it. And that is why our lack of a good implementation is so problematic.
So, what then is the future of BCI execution? I'd put my money, if I had any, into nanotechnology. And not (entirely) because it just sounds futuristic. The fact is, the process of opening up the skull, placing a hard and very foreign object onto the brain, and closing it back up again is never going to be a clean one. We need our BCI devices to be more natural, and to deliver them in a non-invasive way. And the only way to do that is if they are very small, and made of some more bio-friendly materials. And that is exactly what nanotechnology researchers such as John Rogers are working on. His group's recent Science paper (and his appearance on NPR) describes a biodegradable electrode, which could theoretically be implanted in the brain and utilized for diagnostic purposes and then be allowed to dissolve away safely. Longer lasting versions could be used for months or even years. Furthermore, these kinds of 'soft' electrodes can fit better to the curves of the brain, leading to better signal quality. Another nanotech company has developed a coating for traditional electrodes the enhances the signal quality and longevity by reducing the response of the immune system to the electrode. So, through these measures some of the danger of neural implantation can be reduced and the quality of recordings increased.
There is still, however, the issue of delivery. But, do not fear; nanotechnology has the answer to that too! Well, potentially. Because nanomembranes are so small, thin and pliable, they can easily survive being delivered via injection (as this study looking at nano-scaffolds for bone regeneration shows). There is also already precedence for the injection of neural-stimulating electrodes. The BION system involves injecting traditional electrodes into peripheral nerves via a hypodermic needle. Those electrodes are then powered and controlled wirelessly, and allow for stimulation and recording of motor neurons. Now to translate this method into a useful BCI application would require getting the electrodes into the brain, not just the peripheral nervous system. And that is a problem of another magnitude, not easily solved even with nanomembranes in your toolbox. The blood-brain barrier is just annoyingly particular about what it lets thorough. And even if you could get the nanomembrane electrode in, you'd need to have a way to control where it plants itself. Trying to move a prosthetic arm with neural signals coming from your visual cortex is not advisable. So the injection would probably have to be targeted, meaning there are still some serious obstacles to a completely non-invasive procedure. But we have to leave some problems for future scientists...
Maybe the notion of tiny, injectable brain-controlling devices sounds crazy (or terrifying) to you. But it is the general direction we must go in if we want to really utilize all the knowledge that we're painstakingly gathering about how the brain works. Potential applications aren't limited just to disease treatment or prosthetic limb control. Even perfectly healthy people could find BCI beneficial. The gaming industry, for example, has already wet its feet in the BCI pool, using EPOC headsets to add another element of control to games. But these superfluous applications are only sensible if the BCI is incredibly low-risk. No one would endanger their health to make World of Warcraft slightly more entertaining... Ok, maybe some people would, but the FDA isn't going to approve it. So we are a long way off from BCI impacting the everyday life of the average person. But all crazy technology had to start somewhere. I'm excited to see how this particular one develops, and how quickly we can get ourselves into the future.