Just how powerful is the brain of a mouse?

Impressively - especially when you compare it to your average desktop computer. In fact, your computer at home doesn't even come close to matching the power of half a mouse brain: researchers at IBM and the University of Nevada have been using IBM's BlueGene L supercomputer - which contains 4,096 processors, each using 256MB of RAM - and succeeded in simulating a small fraction of the power of just half a mouse brain.

"The mouse cortex has roughly 8x10⁶ (8m) neurons and 8,000 synapses per neuron," state researchers James Frye, Rajagopal Ananthanarayanan and Dharmendra S Modha. "Assuming an average firing rate of 1Hz, the entire memory must be refreshed every second, each neuron must be updated at every simulation time step, and each neuron communicates to each of its targets at least once a second." As the team says in a gloriously deadpan way: "Modeling [sic] at this scale imposes tremendous constraints on computation, communication and memory capacity of any computing platform."

However, even this huge processing effort still only managed to run at a speed 10 times slower than real time, and only for 10 seconds - the equivalent of one second of mouse-thought. Barely enough time for a mouse to register a hungry cat in the vicinity.

Supercomputers are being used in other, more ambitious projects, including a collaboration between IBM and researchers in Switzerland to simulate the human brain. The aim is to provide more understanding of human cognition, including perception and memory.

Flowing from this, the researchers at the Ecole Polytechnique Federale de Lausanne say they might be able to "begin to explain how the brain changed from species to another in evolution". But their work is just the beginning. They point out that the human brain has up to 100bn neurons - compare that to the measly 8m that the Nevada researchers have managed to simulate and you will have some idea of just how much of a leap in processing power the human brain would require.

Would such a supercomputer develop consciousness? The Lausanne researchers are refreshingly candid on this: "We really do not know," they say. "If consciousness arises because of some critical mass of interactions, then it may be possible." That might be useful to know, given that the UK government recently suggested that we might have robots as intelligent as humans by 2050. (Are mice intelligent but not conscious? Or vice-versa?)

Of course according to the Hitchhikers Guide to the Galaxy, mice are in fact the most intelligent life forms on the planet, "a race of hyperintelligent pan-dimensional beings who commissioned the construction of the Earth to find the question to the ultimate answer of life, the universe and everything". Maybe we should simulate rats instead.

http://technology.guardian.co.uk/weekly/story/0,,2070570,00.html