[ExI] Blue Brain Project

[Richard Loosemore]

Ben Zaiboc wrote:
> Anyone not familiar with this can read about it here:
> http://seedmagazine.com/content/article/out_of_the_blue/P1/
> 
> The next ten years should be interesting!

Or not.

Markram is NOT, as many people seem to assume, developing a biologically 
accurate model of a cortical column circuit.  He is instead developing a 
model that contains neurons that are biologically accurate, down to a 
certain level of detail, but with random connections between those 
neurons.  The statistical distribution of wires is supposed to be the 
same as that in a cortical column, but the actual wires... not so much.

So, to anyone who thinks that a randomly mode of an i86 computer chip in 
which all the wiring was replaced by random connections would be a 
fantastically interesting thing, worth spending a billion dollars to 
construct, the Blue Brain project must make you delirious with joy.

Markram's entire project, then, rests on his hope that if he builds a 
randomly wired column model, the model will "self-assemble" and do 
something interesting.  He produces no arguments for what those 
self-assembly mechanisms actually look like, nor does he demonstrate 
that his model includes those mechanisms.

Further, he ignores the possibility that the self-assembly mechanisms 
are dependent on such factors as (a) specific wiring circuits in the 
column, or (b) specific wiring in outside structures (subcortical 
mechanisms, for example) which act as drivers of the self-assembly process.

(To couch this in terms of an example, suppose the biology causes loops 
of ten neurons to be set up all over the column, with the strength of 
synapses around each loop being extremely specific (say, high, high, 
low, high, high, low, high, high, low, low).  Now suppose that the 
self-organizing capability of the system is crucially dependent on the 
presence of these loops.  Since Markram is blind to exact wiring he will 
never see the loops.  He certainly would not see the pattern of synaptic 
strengths, and he probably would never notice the physical pattern of 
the ten-neurons loops, either.)

As far as I can tell, Markram's only reason to believe that his model 
columns will self-assemble is ... well, just a hunch.

If his hunch is wrong, he will have built the world's most expensive 
white-noise generator.

Notice that so far, in the test runs he has done, his evidence that the 
model circuit actually works has all been based on a low-level 
statistical correspondence between the patterns of firing in the model 
and in the original.  Given that he went to great trouble to ensure the 
same distributions in his model, this result gives practically no 
information at all.  Markram does not hesitate to publicize these 
achievements with words that imply that his model column does actually 
"function" like a biological column.  (Going back to the i86 chip 
analogy:  would a statistically similar signal pattern in a random model 
of such a chip indicate that the random model was "functioning" like a 
normal chip?).

There are plenty of other criticisms that could be leveled at the Blue 
Brain project, but this should be enough.

Can you say "Neuroscience Star Wars Project", children?



Richard Loosemore