18 November 2009

Actually, No, IBM Did NOT Simulate a Cat's Brain

Cognitive computing seeks to engineer the mind by reverse engineering the brain. The mind arises from the brain, which is made up of billions of neurons that are liked by an internet like network. An emerging discipline, cognitive computing is about building the mind, by understanding the brain. It synthesizes neuroscience, computer science, psychology, philosophy, and mathematics to understand and mechanize the mental processes. Cognitive computing will lead to a universal computing platform that can handle a wide variety of spatio-temporally varying sensor streams. _Source

Image via Brian Wang
At a supercomputing conference in Portland, Oregon, IBM announced a successful simulation of a "cat brain scale" silicon neuro-computing platform. You can read an engrossing account of this achievement from Dharmendra S. Modha (via Brian Wang).

The achievement is a fascinating one, and worth celebrating. But it would be inaccurate to describe the accomplishment as the simulation of a cat brain. IBM's simulation is nowhere close to a simulation of a cat's brain -- and we should have no illusions regarding the comparison. Consider this:
...using Dawn Blue Gene / P supercomputer at Lawrence Livermore National Lab with 147,456 processors and 144 TB of main memory, we achieved a simulation with 1 billion spiking neurons and 10 trillion individual learning synapses. This is equivalent to 1,000 cognitive computing chips each with 1 million neurons and 10 billion synapses, and exceeds the scale of cat cerebral cortex. The simulation ran 100 to 1,000 times slower than real-time. _ Modha
Some of the neuronal level phenomena observed in the simulation (in response to stimuli) vaguely resembled actual neurocortical electrophysiological activity observed in a mammalian brain. But the parallels are quite loose. And considering the time scale of the simulation was between 100 and 1,000 times slower than real-time, tweaking the stimuli and response to better match mammalian equivalents may take some while.

IBM's simulation of 1 billion spiking neurons was interesting, but a very pale shadow of a genuine cat brain, with all its specialised structural cortical and sub-cortical components -- and accessory (but very influential) glial and vascular infrastructure.

IBM is estimating that around the year 2018, it will be able to simulate a human-scale "brain" in real time. That is preposterous. Only if you accept that IBM has simulated a cat's brain in 2009 would you accept that IBM may simulate a human brain by 2018. But as IBM readily admits, it has not even simulated a cat's multi-specialised cortex -- much less a cat's entire brain.
In terms of details in our simulations, we are currently working on differentiating our cortical region into specific areas (such as primary visual cortex or motor cortex) and providing the long-range connections that form the circuitry between these areas in the mammalian brain. For this work, we are drawing from many studies describing the structure and input/output patterns of these areas as well as a study recently performed within IBM that collates a very large number of individual measurements of white matter, the substrate of long-range connectivity within the brain. _Modha
Give them time. I expect some amazing results from this approach to brain simulation, eventually. Unfortunately, neither the hardware nor the software tools are anywhere close to providing scientists with a semi-realistic mammalian brain at this time.

Even a realistic insect brain would be a marvelous achievement. Particularly one that operated in real time, and was sized on roughly the same scale as an actual insect.

So while Al Fin cognitive neuroscientists, engineers, and cognitive computing specialists congratulate IBM on its latest achievement, they also caution IBM not to overstate what they have actually accomplished.

25 Nov 2009 Update: Be sure to read Henry Markram's response to the IBM claims at Brian Wang's site (and in comments here).

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Blogger Henry said...

Dear Al,

Just to set the record straight. This is not a record number of point neurons in a simulation, so it is even not a technical achievement. Izhikevik simulated 100 Billion point neurons just for fun with desktop computers (60 times larger). The Human Brain has around 100 Billion neurons, but that does not mean it is a Human Brain simulation. This was already done in 2005.

See: http://www.izhikevich.org/human_brain_simulation/Blue_Brain.htm#Simulation%20of%20Large-Scale%20Brain%20Models

As for simulators, there are many that can do this on supercomputers and the number of point neurons that can be simulated is just limited by their memory.

Tuesday, 24 November, 2009  
Blogger al fin said...

Thanks for the comment and link, Henry.

I agree that 1.6 billion silicon "neurons" do not make a cat brain (or visual cortex), and 100 billion silicon "neurons" will not make a human brain.

I, too, have concerns with over-ambitious predictions and claims for future achievements.

I admire the effort being put into the attempt to build artificial brains. It is an immense challenge.

Good luck in your own work -- I hope you succeed, although I suspect the time scale involved may be longer than you might have wished.

Wednesday, 25 November, 2009  

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