In the coming years, there will be many grand announcements about supercomputers that attempt to imitate the machinery inside the skull. One way to distinguish between such claims is to look at their cellular realism: Are these microchips really behaving like neurons? Or has the simulation taken a shortcut, and turned our neurons into dumb little microchips? Because we sometimes forget that the “mind is like a computer” metaphor is only a metaphor. The mind is really just a piece of meat.

[Source: The Frontal Cortex]

An interdisciplinary team of researchers at IBM have presented at paper at the SC09 supercomputing conference describing a milestone in cognitive computing: the group’s massively parallel cortical simulator, C2, now has the ability to simulate a brain with about 4.5 percent the cerebral cortex capacity of a human brain, and significantly more brain capacity than a cat.
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The simulator, which runs on the Dawn Blue Gene /P supercomputer with 147,456 CPUs and 144TB of main memory, simulates the activity of 1.617 billion neurons connected in a network of 8.87 trillion synapses. The model doesn’t yet run at real time, but it does simulate a number of aspects of real-world neuronal interactions, and the neurons are organized with the same kinds of groupings and specializations as a mammalian cortex. In other words, this is a virtual mammalian brain (or at least part of one) inside a computer, and the simulation is good enough that the team is already starting to bump up against some of the philosophical issues raised about such models by cognitive scientists over the past decades.

In a nutshell, when a simulation of a complex phenomenon (brains, weather systems) reaches a certain level of fidelity, it becomes just as difficult to figure out what’s actually going on in the model—how it’s organized, or how it will respond to a set of inputs—as it is to answer the same questions about a live version of the phenomenon that the simulation is modeling. So building a highly accurate simulation of a complex, nondeterministic system doesn’t mean that you’ll immediately understand how that system works—it just means that instead of having one thing you don’t understand (at whatever level of abstraction), you now have two things you don’t understand…

[Source: Ars Technica]

Of course, unlike a real brain, the computer simulation can be tweaked, recoded, expanded and run at will. Things can be learned from that, but the point remains – although in the not to distant future computers will be able to carry out the same number of calculations as a human brain, until we know how the brain works, we won’t be getting a functional equivalent from a computer. That breakthrough is down the trail, maybe a decade or three.