The nematode Caenorhabditis elegans is one of the simplest microanimals around. C. elegans has the distinction of being the only animal whose entire connectome has been uploaded to a computer. A connectome is a map of all the neural connections in the nervous system of an organism, which can be thought of like a wiring diagram. It is a computer worm like no other. There is a virtual copy of the brain and nervous system of an entire organism, and it is even open source! You can get your hands on the digitised organism at the OpenWorm project.
This is not a computer program, it is an actual digital copy of the worm. Even with the simple nervous system, the tiny worm can navigate, eat bacteria and respond to touch. If the worm feels a touch, it wriggles away. The digital version of the worm reacts to a simulated touch in the same way as the real nematode would, simply because the response is hard coded in the neural network of the organism. That response was used to teach the worm a new trick – to balance a pole.
Balancing a pole is a routine problem in computer science. Whenever the pole tilts, the base has to be shifted to compensate for the tilt, keeping the pole straight. The researchers mapped the tilting of the pole to the touch response, and trained the worm to balance a virtual pole. Mathias Lechner, who worked on the project, explains, “With the help of reinforcement learning, a method also known as ‘learning based on experiment and reward’, the artificial reflex network was trained and optimized on the computer.” Radu Grosu, another researcher on the project, elaborates, “The result is a controller, which can solve a standard technology problem – stabilizing a pole, balanced on its tip. But no human being has written even one line of code for this controller, it just emerged by training a biological nerve system.”
The researchers from TU Wien achieved the feat without adding any new neurons to the digital worm, but only by tuning the strength of the connections between the virtual neurons. The team plants to further explore the potential possibilities of similar controlling circuits.
This begs the question, can the process be applied to a human being? C. elegans has only 300 neurons in its entire body, with about 7,000 connections between them, so mapping and uploading the connectome was relatively simple. In fact, it was done back in 1986. There are one hundred billion neurons in the human brain, and a quadrillion connections, so it is much more complex to create the human connectome. That is just in the brain, not the entire nervous system. However, the Human Connectome Project is an effort to achieve just that.
Source: TU Wien