Synthetic Brain? Researchers Achieve Artificial Brain Function Using Nanotechnology

Posted by: Andrew Kolbenschlag on April 28, 2011 at 11:01AM
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A First Step Toward Brain Prosthesis?

Professors Alice Parker and Chongwu Zhou have led an interdisciplinary team of researchers in an attempt to artificially recreate a synaptic circuit. The professors published their results in a paper titled "A Biomimetic Carbon Nanotube Synapse Circuit" at the 2011 Life Science Systems and Applications Workshop this month. Parker, who has been researching synthetic neuroscience for five years, described the team's work as "a necessary first step" toward the possibility of creating viable brain prosthesis, treating traumatic brain injuries, or even developing a completely synthetic brain.

Carbon Nanotubes

Carbon nanotubes are extremely small, cylindrical molecular carbon structures. The average size of nanotubes is about 1 or two nanometers, with each nanometer equal to one billionth of a meter. The tubes possess incredible strength, ranging anywhere from five to fifty times the strength of steel. They also make great electrical conductors, and have already seen use in electrical circuits. Due to the inherent complexities that any future neurological biomimetic technology would have to account for, the paper cites the small size of carbon nanotubes as a necessary aspect of any component that may be seriously considered for a future brain prosthesis.

"Single-walled carbon nanotubes avoid most of the fundamental scaling limitations of silicon devices," according to the paper, "and appear to be an appropriate technology for a synthetic cortex."

Synapses and Neurons

Synapses represent an integral aspect of information exchange within the human brain. A synapse is a small gap between neurons, across which information derived from various stimuli flows from one neuron to another in the form of electrical or chemical signals. These signals are responsible for sensory perception -- pain, pleasure, etc. -- and are extremely complex. Neurons do not always transfer information in the same way. Presynaptic neurons (the cells that are sending the information) can alter the intensity of neurotransmitters released or voltage transmitted, in chemical synapses and electrical synapses, respectively. This results in an astounding degree of complexity within the brain.

The paper points to such intricacies as evidence that functioning synthetic cortex models are probably "decades away." The average human brain contains a few hundred trillion synapses, with about a trillion in each cubic centimeter of cerebral cortex. But it is important to note that the researchers did not set out to replicate a human brain -- they set out to examine the functionality of nanotubes in the construction of one such artificial synaptic circuit, a task the papers describes as "important in understanding the future prospects for a synthetic cortex."

"We wanted to answer the question," says Parker, "Can you build a circuit that would act like a neuron?" Now that they have succeeded in doing so, "The next step is even more complex. How can we build structures out of these circuits that mimic the neuron, and eventually the function of the brain, which has 100 billion neurons, (each of which has between) 10,000 (and 100,000) synapses?”

The team's paper can be found here.

Above carbon nanotube image © Chris Ewels.