This article was first published in the December 2015 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
Biodigital brains are made by fusing chips with brain tissue. The technology is racing beyond most people's ability to comprehend the potential to transform how we think and feel. As a physician, I'm fascinated.
More than 400,000 human beings already have a digital device inside their heads, with more than 50,000 new surgical operations taking place every year. Most of these devices are connected to the auditory nerve as cochlear implants, to treat deafness, and a few to the optic nerve or the retina. But a rapidly growing number of people have chips which are directly fused with their own brains.
In many cases, this is to help control involuntary tremors in Parkinson's disease. In other cases, the aim is to give muscle control to paralysed people. For example, Erik Sorto is a tetraplegic who moves his robotic arm by thinking, using an implanted device created by Caltech.
Connecting brains to chips is really easy -- once you have got the chip safely embedded inside someone's head. Brain cells instantly recognise digital intelligence, because both chips and brain cells use tiny electrical signals to communicate.
For over 20 years, scientists have been growing biodigital brains, using rat or mouse brain cells and specially prepared neurochips, with roughened areas to enable brain cells to stick in place, coated with special proteins.
Each brain cell grows small branches across the chip surface, searching for life. When a branch picks up an electrical signal from another nerve cell, it forms a connection or synapse. The same happens if it picks up a signal from the surface of the chip. So your brain is programmed to recognise and install such devices automatically, though bio-software may need to be developed.
The first experiments with implanted biodigital devices were in rats in 1993. And in 2013, Miguel Nicolelis at Duke University reported that two rats had begun sending virtual messages to each other, brain to brain. He has since created a brain network between four rats, each of which passed sensory data to the other animals, which they used collectively to solve tasks better.
The first biodigital devices in humans were used to deliver visual data directly to the optic cortex of the brain in blind people, bypassing the optic nerve. For over a decade, other implanted devices have allowed paralysed people to control external equipment, or their own limbs.
Command, control and delivery of sensory data are relatively straightforward, but creating digital memory storage for the brain is far harder. Sending an enquiry from brain cells to a biodigital device, and making sense of the answer, is very different from making a simple connection.
There are two health challenges: one immediate and the other very long term. Getting a chip into place means drilling a hole in the skull and cutting through membranes that cover the brain. And after the operation, the chip can irritate the brain, with a risk of epilepsy. Many first-generation devices need permanent wires, which create risks of infection. Tomorrow's devices, however, will be wireless and charged remotely.
But here is the issue with all these innovations. Ask any conference audience whether they would like a biodigital brain implant and they always say the same thing. Interesting, important maybe to help repair damaged people, but it is not something they would want for themselves or their children. Even if you promise extra memory or super-intelligence.
What we learn from this is a fundamental truth about all digital innovation. You may have the smartest device, app, online tool or capability in the world, but adoption depends hugely on how people feel about it. And feelings can change rapidly.
Predicting emotion, mood and deeper human needs is often more important than the innovation itself.