It's probably still going to be a while before autonomous, self-aware androids are wandering amongst us. That scenario has come a little closer to reality, however, with researchers from the University of Southern California having created a functioning synapse circuit using carbon nanotubes. An artificial version of the connections that allow electrical impulses to pass between neurons in our brains, the circuit could someday be one component of a synthetic brain.

The USC Viterbi School of Engineering team was led by Professors Alice Parker and Chongwu Zhou. Parker has been looking into the feasibility of creating a synthetic brain for the past five years, as part of the BioRC Biomimetic Real-Time Cortex project.

The circuit itself consists of highly-aligned carbon nanotubes that are grown on a quartz wafer, then transferred to a silicon substrate. It mimics an actual synapse insofar as the waveforms that are sent to it, and then successfully output from it, resemble biological waveforms in shape, relative amplitudes and durations. In other words, it can take in the type of impulses generated by real neurons, and send them on in a form that could be further processed by other neurons - it can even vary the strength of those impulses, much as real synapses do in a biological process that is thought to facilitate learning.

A schematic of USC's synapse circuit

"This is a necessary first step in the process," said Parker. "We wanted to answer the question: Can you build a circuit that would act like a neuron? 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?"

While Parker stated that synthetic brains are probably still decades away, she believes that the technology could ultimately be used in prosthetic nanotechnology for treating traumatic brain injuries, or for designing intelligent systems that could be used to make cars safer, among other applications.