Artificial neural network made out of DNA

Artificial intelligence has been the inspiration for countless books and movies, as well as the aspiration of countless scientists and engineers.

Researchers at the California Institute of Technology have now taken a major step toward creating artificial intelligence—not in a robot or silicon chip, but in a test tube. The researchers, according to a press release, are the first to have made an artificial neural network out of DNA, creating a circuit of interacting molecules that recall memories based on incomplete patterns, similar to the working of a brain.

“The brain is incredible,” says Lulu Qian, a Caltech senior postdoctoral scholar in bioengineering and lead author on the paper published in the July issue of the journal Nature. “It allows us to recognise patterns of events, form memories, make decisions, and take actions. So, we asked, instead of having a physically connected network of neural cells, can a soup of interacting molecules exhibit brain-like behaviour?”

The answer, the researchers say, is yes. Consisting of four artificial neurons made from 112 distinct DNA strands, the researchers’ neural network plays a mind-reading game in which it tries to identify a mystery scientist from four scientists. After thinking of a scientist, a human player provides an incomplete subset of answers that partially identify the scientist. The player then passes those clues to the network by dropping DNA strands that correspond to those answers into the test tube. This DNA-based neural network demonstrates the ability to take an incomplete pattern and figure what it might represent—one of the brain’s unique features.

Biochemical systems with artificial intelligence, or at least some basic, decision-making capabilities, could have powerful applications in medicine, chemistry, and biological research, researchers say. In the future, such systems could operate within cells, helping to answer fundamental biological questions or diagnose a disease.