Scientists to Build 'Brain Box'

lee1 writes "Researchers at the University of Manchester are constructing a 'brain box' using large numbers of microprocessors to model the way networks of neurons interact. They hope to learn how to engineer fail-safe electronics. Professor Steve Furber, of the university school of computer science, hopes that biology will teach them how to build computer systems. He said: 'Our brains keep working despite frequent failures of their component neurons, and this "fault-tolerant" characteristic is of great interest to engineers who wish to make computers more reliable. [...] Our aim is to use the computer to understand better how the brain works [...] and to see if biology can help us see how to build computer systems that continue functioning despite component failures.'"

Comments

Re:Testing for fault tolerance

[CroDragn]

This has been done before, introducing a random element into the neural net. If done correctly, this can result in "creativity". Here is one link about it, seen it many other places too, so google for more.

some amusing calculations

[llZENll]

well the article is so short its not possible to comment on their implementation. so here are some calculations i did to amuse myself.

number of neurons in the brain: 100 billion
http://hypertextbook.com/facts/2002/AniciaNdabahal iye2.shtml

transistor count per CPU: ~300 million
http://www.anandtech.com/cpuchipsets/showdoc.aspx? i=2795

average synaptic connections per neuron: 7000
http://en.wikipedia.org/wiki/Neuron

total number of synapses: 100 to 500 trillion

since a 'calculation' for one artificial neuron mostly involves a summation of weights, we can view one total step as 2 X the number of synapses we wish to analyze. or 200 - 1000 trillion calculations for one step. by step i mean summing all inputs and pushing the result to an output for each neuron.
http://en.wikipedia.org/wiki/Artificial_neuron

fastest computer in the world FLOPs: 280 trillion
http://en.wikipedia.org/wiki/Blue_Gene

pentium 4 FLOPs: 40 GFLOP

using the fastest computer in the world 1 step would only take around 1 - 5 seconds, not counting storing all of that information.
http://en.wikipedia.org/wiki/Blue_Gene

so how fast do we think? well i couldn't find anything on this so lets get a quick estimate. the average neuron is .1m in length .1 / c = 3.3x10^-10 or 333 picoseconds. now lets add in some delay for the chemicals in the neurons to do their thing, this is probably much slower than the electrical impulse, so lets say 3.3 nanoseconds.

so assuming our computers could network instantly, and store the data used instantly, we would need 3-15 trillion Blue Gene supercomputers to simulate the human brain in real time. or if we are using pentium 4s we would only need 21-105 trillion pentium 4s.

man thats a lot of cpus.

number of computers in the world: ~300 million
http://www.aneki.com/computers.html
guess at average FLOPs per computer: 40 GFLOPs
total FLOPs of worlds personal computers: 1.2 PFLOPs
time to calculate one brain step if all computers in the world were networked: .2 - .8 seconds

using moores law, when will a single computer be fast enough to simulate the human brain in real time?
200-1000 trillion calculations per step = ~600 trillion every 3.3ns = 181x10^18 or 181exeFLOPs
181exaFLOPS / 40GFLOPS = 2^n, n=32
32*18mo = 48 years based on personal computer technology

or 28 years based on supercomputer technology

of course a real neural network will contain highly parallel processing and using a specific chip design we will probably be able to simulate a brain much sooner, perhaps in the order of 10-20 years.