“Patching into the brain” is a staple of science fiction and you hear about it fairly often in neuroscience; connecting ‘wires’ into the brain somehow seems routine. It’s not. Scientists and sometimes doctors do lots of things with reading or probing the brain with external (on the skin) sensors. They also occasionally do neural implants of one kind or another, usually electrical stimulus or probe devices placed strategically in a brain location. Any time the brain is approached with an invasive technology (makes actual physical contact with brain tissue); it’s a tricky and often dangerous business. Most of the research is done with animals.
What is not yet available is a reliable, non-destructive, relatively safe way to connect with the elements, for example axons, of specific neurons. As an example of a new approach to connecting neurons and as an example of a new use of nanotechnology, researchers at the University of Wisconsin (Madison, USA) led by Justin Williams found that by seeding areas outside of variously shaped nanotubes (in this case extremely fine tubes of layered silicon and germanium) with mouse neurons, the neurons produced axons (filaments) that would readily enter and grow through the tubes. The results published in ACS Nano, 2 March 2011, [Semiconductor Nanomembrane Tubes: Three-Dimensional Confinement for Controlled Neurite Outgrowth] represent the kind of ‘could-be really important’ research, very early in its development, or it could be very little at all.
The important thing with this approach is the ability to take a semiconductor material (the silicon/germanium tube) and non-destructively mate it with neural material. The tubes are coated with amino acids that attract neuron growth, which according to the experiment works quite well. At the moment, using the tubes makes it possible to control the growth pattern of selected neurons so that experiments with connection shapes and designs can be performed. This may be useful, but the real potential is down the road.
The portions of the neuron growing down the tubes are the transmitter elements. The next step in the research is to put nanoscale sensors and transmitters into the tube material so that electrical and electro-chemical activity in the neurons can be detected. This would allow neuroscientists to monitor the activity of individual neurons and at least some of their connections to other neurons. (A single neuron usually has thousands of such connections.)
Eventually – read: many years – it might be possible to use this technique to make a truly controlled and targeted interconnection between neurons and electronic implants (or other electronic devices). In a way it would be like putting conductive sleeves on electrical wires, so that the current can be measured, tapped, augmented or otherwise controlled. From this use of nanotechnology could follow a much better way to hook-up prosthetic devices or make brain implants. The engineering challenge, however, is great. At this point the researchers don’t even know if the neurons are sending signals through the axons in the tubes, much less whether a tissue of such nanotube connected neurons will function in any way like a normal group of neurons. Nevertheless, this is intriguing science and technology – the kind of stuff that provokes the imagination.
See also: World of Weird Things blog – Moving one inch close to real world wetware