A bit of an update in Seed magazine on the Blue Brain project. This is the project that set out to simulate the brain by actually reproducing it in full biological detail down to the behaviour of individual neurons and beyond: with some success, it seems.
The idea of actually simulating a real brain in full has always seemed fantastically ambitious, of course, and in fact the immediate aim was more modest: to simulate one of the columnar structures in the cortex. This is still an undertaking of mind-boggling complexity: 10,000 neurons, 30 million synaptic connections, using 30 different kinds of ion channel. In fact it seems the ion channels were one of the problem areas; in order to get good enough information about them, the project apparently had to set up its own robotic research. I hope the findings of this particular bit of the project are being published in a peer-reviewed journal somewhere.
However, the remarkable thing is that it worked: eventually the simulated column was created and proved to behave in the same way as a real one. So is the way open for a full brain simulation? Not quite. Even setting aside the many structural challenges which surely remain to be unravelled (don’t they – the brain isn’t simply an agglomeration of neocortical columns?) Henry Markram, the project Director, estimates that an entire brain would require the processing of 500 petabytes of data, way beyond current feasibility. Markram believes that within ten years, the inexorable increase in computing power will make this a serious possibility. Maybe: it doesn’t pay to bet against Moore’s Law – but I can’t help noticing that there has been a big historical inflation in the estimated need, too. Markram now wants 500 petabytes: a single petabyte is 1015 bytes; but in 1950 Turing thought that 1015 bits represented the highest likely capacity of the brain, with about 109 enough for a machine which could pass the Turing Test. OK, perhaps not really a fair comparison, since Turing had nothing like Blue Brain in mind.
One criticism of the project asks how it judges its own success – or rather, suggests that the fact that it does judge its own success is a problem. If we had a full brain which could operate a humanoid robot and talk to us, there would be no doubt about the success of the project; but how do we judge whether a simulated neuronal column is actually working? The project team say that their conclusions are based on scrupulous comparisons with real biological brains, and no doubt that’s right; but there’s still a danger that the simulation merely confirms the expectations fed into it. They came up with an idea of how a column works; they built something that worked like that: and behold, it works how they think a column works.
There is also undeniably something a bit strange about the project. Before Blue Brain was ever thought of, proponents of AI would sometimes use the idea of a total simulation as a kind of thought-experiment to establish the merely neurological nature of the mind. OK, there might be all these mechanisms we didn’t understand, and emergent phenomena, and all the rest, but at the end of the day, what if we just simulated everything? Surely then you’d have to admit, we would have made an artificial mind – and what was to stop us, except practicality? It was an unexpected development back in 2005 when someone actually set about making this last-ditch argument a reality. It is unique; I can’t think of another case where someone set out to reproduce a biological process by building a fully detailed simulation, without having any theory of how the thing worked in principle.
This raises some peculiar possibilities. We might put together the full Blue Brain; it might be demonstrably performing like a human brain, controlling a robot which walked around and discussed philosophy with us, yet we still wouldn’t know how it did it. Or, worse perhaps, we might put it all together, see everything working perfectly at a neuronal level, and yet have our attached robot standing slack-jawed or rolling around in a fit, without our being able to tell why.
It may seem unfair to describe Markram and his colleagues as having no theory, but some of his remarks in the article suggest he may be one of those scientists who doesn’t really get the Hard Problem at all.
…It’s the transformation of those cells into experience that’s so hard. Still, Markram insists that it’s not impossible. The first step, he says, will be to decipher the connection between the sensations entering the robotic rat and the flickering voltages of its brain cells. Once that problem is solved—and that’s just a matter of massive correlation—the supercomputer should be able to reverse the process. It should be able to take its map of the cortex and generate a movie of experience, a first person view of reality rooted in the details of the brain…
It could be that Markram merely denies the existence of qualia, a perfectly respectable point of view; but it looks as if he hasn’t really grasped what they are, and that they can’t be captured on any kind of movie. Perhaps this outlook is a natural or even a necessary quality of someone running this kind of project. I suppose we’ll have to wait and see what happens when he gets his 500 petabyte capacity.
1. Bob Eichler says:
Another blog you might be interested in.
http://mindandcognition.blogspot.com/
March 10, 2008, 8:43 pm2. Malcolm Pollack says:
Set aside is the possibility that subjective consciousness (and I think most of us would agree that we haven’t duplicated the human mind without including that) arises, as Searle or Penrose might interject, in virtue of some physical particulars of the brain’s biological instantiation.
March 11, 2008, 1:55 am3. Lloyd Rice says:
Really 500 petabytes? No, no no. Suppose one of us landed on Henry Ford’s doorstep
in, say, 1890, with our terabyte laptop. We said, “Henry, here is something fantastic.
We can simulate a horse’s hoof. Just imagine where we can go from here!!!”
I say we have to be a bit more careful about what question we are asking.
Do we want to get from place to place or do we want to simulate a horse?
Is it even on the right track to simulate a cortical column? Maybe yes, if that’s
March 12, 2008, 3:17 amwhat the question is. But that’s not the question which will be answered by
knowing what the brain does. It’s closer to asking how the brain works.
Maybe that’s what you want to ask, maybe not. I want to know what it does,
not necessarily how it does it.
4. Lloyd Rice says:
I don’t at all belittle Dr. Markram’s work. I believe it’s a necessary step
March 12, 2008, 8:07 pmtoward learning how it all works. But I have to agree with Terry Sejnowski
that we’re still a long way from knowing how to interconnect 100 or 1,000,000
Blue Brains to make a bigger part of a brain.
5. Eric Thomson says:
We’ve had a little back-and-forth on the same topic at philosophyofbrains, here. I like this approach, and discuss it in a little detail at the link. Of course ultimately we’ll want these super-detailed models to be integrated with psychological theorizing and the like.
I’m surprised by one thing you didn’t mention: this thing is going to generate tons of predictions about the behavior of cortical neurons. The model isn’t right just because they built in detail: we’ll be able to tell how good the model is by comparing its behavior to that of real neurons, and then the theory and data will co-evolve until we have good reason to really believe what the model is telling us. That’s where the real fun begins for the theorists.
March 12, 2008, 9:37 pm6. Peter says:
Thanks, Bob – looks interesting.
Fair point, Eric. I don’t know what the support for the next phases of the project is like (I presume IBM and EPFL are in this for the long run), but I certainly hope it continues long enough to realise those possibilities.
March 13, 2008, 10:05 am7. whats in a name says:
As everyone I am very curious to know about the brain. What is interesting to me is how
January 7, 2010, 3:44 pmthis information is collected. Could it be that one day the scientists who did all this wonderful work – would find themselves in hot water because maybe they “forgot” to ask for consent of the individual who they have been “stalking”. I do not think that humanity is proud of the experiments that were performed by the Nazi on humans with out their consent.