Connectionists: How the brain works

[Axel Hutt]

I fully agree with Thomas and appreciate, once more, the comparison with physics. 

Neuroscientists want to understand how the brain works, but maybe this is the wrong question. In physics, 
researchers do not ask this question, since, honestly, who knows how electrons REALLY move around 
the atom core ? Even if we know it, this knowledge is not necessary, since we have quantum theory that tells uns something about 
probabilities in certain states and this more abstract (almost mesoscopic) description is sufficient to 
explain large scale phenomena. Even on a smaller scale, quantum theory works fine, but only since physicists 
DO NOT ASK what electrons do in detail, but accept the concept. In contrary, todays neuroscience ask 
questions on all the details, what why ? Probably it is better to come up with a "concept" or more abstract 
model on neural coding, for sure on multiple description levels. But I guess, looking into too much much 
(neurophysiological) detail slows us down and we need to ask other questions, maybe more directing 
towards experimental phenomena. 

A good example is the work of Hubel and Wiesel and the concept of columns (I know Jim and others do not like 
the concept), based on experimental data and deriving such a kind of concept. Of course these columns are not there 
'physically' (there are no borders) but they represent more abstract functional units which allow to explain certain 
dynamical features on the level of neural populations (e.g. in the work on visual hallucinations). Today this concept 
is largely attacked since biologists 'do not see it'. But, again going back to physics, the trajetories of single electrons in 
atoms have not been measured yet and so the probability densi ty of their location has not been computed yet from 
the single trajectories, but the resulting concept of probability orbits of electrons is well established today since it 
works well. 

Another analogy from physics (sorry to bore you, but I find the comparison important): do you believe that an 
object changes when you look at it (quantum theory says so) ? No, sure not, since you do not experience/measure it. 
But, hey, the underlying quantum theory is a good description of things. What I want to say: in neuroscience we 
need more theory based on physiological (multi-scale) experiments that describes the found data and permit to accept 
more (apparently) abstract models and get rid of our dogmatic view on how to do research. If an abstract description 
explains well several different phenomena, then per se it is a good concept (e.g. like the neural columns concept). 

Well, I have to go back to theoretical work, but it was very nice and stimulating attending this discussion. 

Axel 

----- Original Message -----

> Some of our discussion seems to be about 'How the brain works'. I am
> of course not smart enough to answer this question. So let me try
> another system.
> How does a radio work? I guess it uses an antenna to sense an
> electromagnetic wave that is then amplified so that an electromagnet
> can drive a membrane to produce an airwave that can be sensed by our
> ear. Hope this captures some essential aspects.
> Now that you know, can you repair it when it doesn't work?
> I believe that there can be explanations on different levels, and I
> think they can be useful in different circumstances. Maybe my above
> explanation is good for generally curious people, but if you want to
> build a super good sounding radio, you need to know much more about
> electronics, even quantitatively. And of course, if you want to
> explain how the electromagnetic force comes about you might need to
> dig down into quantum theory. And to take my point into the other
> direction, even knowing all the electronic components in a computer
> does not tell you how a word processor works.
> A multilayer perception is not the brain, but it captures some
> interesting insight into how mappings between different
> representations can be learned from examples. Is this how the brain
> works? It clearly does not explain everything, and I am not even
> sure if it really captures much if at all of the brain. But if we
> want to create smarter drugs than we have to know how ion channels
> and cell metabolism works. And if we want to help stroke patients,
> we have to understand how the brain can be reorganized. We need to
> work on several levels.
> Terry Sejnowski told us that the new Obama initiative is like the
> moon project. When this program was initiated we had no idea how to
> accomplish this, but dreams (and money) can be very motivating.
> This is a nice point, but I don't understand what a connection plan
> would give us. I think without knowing precisely where and how
> strong connections are made, and how each connection would influence
> a postsynaptic or glia etc cells, such information is useless. So
> why not having the goal of finding a cure for epilepsy?
> I do strongly believe we need theory in neuroscience. Only being
> descriptive is not enough. BTW, theoretical physics is physics.
> Physics would not be at the level where it is without theory. And of
> course, theory is meaningless without experiments. I think our point
> on this list is that theory must find its way into mainstream
> neuroscience, much more than it currently is. I have the feeling
> that we are digging our own grave by infighting and some narrow 'I
> know it all' mentality. Just try to publish something which is not
> mainstream even so it has solid experimental backing.
> Cheers, Thomas
-- 

Dr. rer. nat. Axel Hutt, HDR 
INRIA CR Nancy - Grand Est 
Equipe NEUROSYS (Head) 
615, rue du Jardin Botanique 
54603 Villers-les-Nancy Cedex 
France 
http://www.loria.fr/~huttaxel 
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