Carbon Nanotube Neuron Interface

Carbon nanotubes are composed of carbon atoms arranged in a honeycomb pattern bended in a round tube shape. They are only a few nanometers in size, about 1/50,000th of the width of a human hair. Carbon nanotubes have a variety of interesting properties and are conductors of electricity. Research from a year ago demonstrated that neurons grown on carbon nanotubes had increased electrical activity. Surprisingly neurons can grow very well on these carbon nanotubes. Devices based on carbon nanotubes may lead to better deep brain stimulation implants or brain computer interfaces.

Recently researchers have found that the increased activity of the neurons on the carbon nanotubes results partly from electrical signals propogating through the carbon nanotubes themselves. The researchers used hippocampus brain cells attached to a fullerene nanotube. At the level of a neuron, there are a variety of constraints to the processing of neural information. These constraints include the time it takes for neurotransmitters to diffuse across the synaptic cleft and the speed of electrochemical signals down the axons and dendrites of the neurons. The electrochemical signals that move down the axon of a neuron are much slower than electricity moving through a carbon nanotube. According to one researcher "This kind of substrate can actually work as a kind of shortcut between two points of a network of neurons, or two points of the same cell". The team that is performing this research wants to use it to help those with spinal cord injuries. Other researchers have indicated that carbon nanotubes could potentially have some negative effects on neuron excitability as well depending on specific factors.

Could carbon nanotubes allow researchers to vastly accelerate the brain's processing speed and drastically alter our perception of time? Could interneuronal connections be replaced or enhanced with carbon nanotube junctions? At this point probably not. Neurons can only fire at a specific rates and these types of connections probably wouldn't change that. Without some massive reengineering of the brain it would probably either completely mess up the brain's dynamics or just add noise to the brain's computational capacity depending on the extent of added nanotubes. There would not be a subsequent increase in brain processing speed. A lot of the brain's processes are emergent phenomenon that depend on the brain's massive parrallelism. The additive effects of trillions of slow interneuronal connections create a unitary conscious experience with a difficult to quantify overall brain processing speed construct. Arbitrarly speeding up connections at one "level" (atomic level) of brain activity is no guarantee that you would beneficially alter higher "levels" of activity (aggregate neuron firing rates). Whole brain processing speed is probably due to additive effects at a variety of brain "levels".

Carbon nanotubes as scoffolding, though, may enable researchers to repair specific tissue damage with stem cell synthesized brain matter. Or the nanotubes could serve as a replacement junction connection for single neurons. Brain implants based on carbon nanotubes could treat a variety of brain disorders. Perhaps in the future we will have more sophisticated brain computer interfaces that will make full use of the transmission speed and the computational capacity of carbon nanotubes.

You can read more at nature.