Chris Eliasmith has spent years contemplating how to build a brain. Eliasmith's team built Spaun, which was billed Thursday as "the world's largest simulation of a functioning brain."
Spaun can recognize numbers, remember lists and write them down. It even passes some basic aspects of an IQ test, the team reports. Spaun, which stands for Semantic Pointer Architecture Unified Network, has 2.5 million simulated neurons organized into subsystems to resemble the prefrontal cortex, basil ganglia, thalamus and other cognitive machinery in the brain. It also has a simulated eye that can see, and an arm that draws.
The simplified model of the brain, which took a year to build, captures many aspects of neuroanatomy, neurophysiology and psychological behaviour, says Eliasmith, director of Waterloo's Centre for Theoretical Neuroscience. Spaun's cognition and behavior is very basic, but it can learn patterns it has never seen before and use that knowledge to figure out the best answer to a question. "So it does learn," says Eliasmith.
But it is not - at least not yet - a match for the real thing. "Spaun is not as adaptive as a real brain, as the model is unable to learn completely new tasks," the team reports in Science. "In addition, both attention and eye position of the model is fixed, making Spaun unable to control its own input."
Eliasmith is now working with groups in the US and Britain to try speed up Spaun and expand its tasks and behaviors. He says such brain simulations might one day be used to better understand and model neurological disorders and diseases and to improve "machine intelligence."
Eliasmith notes that humans have about 100 billion neurons in their brains, far more than other animals and artificial brains taking in shape in the lab. Today's "smart" machines can play chess, backgammon and act as personal assistants, like Siri on Apple's iPhone, but Eliasmith says the processes they use have little in common with the brain. He says it hard to predict the future, but he expects to see an explosion in artificial intelligence and more "human-like" machines." A robot that is able to navigate through a city and deliver a package from one place to another," he says. "I think that kind of thing will be within reach in the next 10 years."