[Comp-neuro] Discussion - Kuhn - and brief comments

Garrison Cottrell gary at cs.ucsd.edu
Wed Sep 3 17:30:06 CEST 2008


I hate to jump into this, but...

Speaking as a true novice, I would like to point out that the  
neurogenesis that occurs on a daily basis is very specific to the  
dentate gyrus; if someone knows of "daily neurogenesis" elsewhere, I  
would like to hear about it.

This is not the same as learning in an ANN - these new neurons have a  
specific function, which some of the best minds in our field are  
currently trying to figure out (see Aimone, J., Wiles, J., & Gage, F.  
(2006). Potential role for adult neurogenesis in the encoding of time  
in new memories. Nature Neuroscience, 9(6), 723-727. for one example).

It is only if you don't have a good weight change rule (e.g., STDP)  
and/or you believe in localist encodings that you need neurogenesis to  
learn.

(shields up! ;-))

g.

On Sep 2, 2008, at 12:50 PM, Asim Roy wrote:

> Asim Roy:  "a "blank slate" simply implies a network whose  
> connection weights and other parameters have not been set yet -"
>
> Jim Bower's response: And, no such thing in biology, where  
> development doesn't end and learning begins - it is continuous, and  
> development probably recapitulating evolutionary history.  Another  
> reason why the mainstream ANN models make no sense.
>
>
> Jim, would love to get some references for your statement:-  
> "development probably recapitulating evolutionary history." This  
> really is the kind of process in the brain that I am looking for.  
> Just a few references would suffice.
>
> By the way, learning takes place during development too. Just ask  
> anyone in cognitive science. Development is not disassociated from  
> learning. And ANN never implied learning begins after development.  
> That's a misconception.
>
> On the "blank slate" idea in ANN, just look at the phenomenon of  
> adult neurogenesis. Our adult brains generate new cells in the  
> thousands on a daily basis and they are part of the "blank slate"  
> because they don't come with ready-made connections or anything. The  
> process that you refer to as "development probably recapitulating  
> evolutionary history" is called "learning" in ANN. It's that process  
> that constructs networks out of these new cells and makes them  
> operational.
>
> Asim  Roy
> Arizona State University
>
>
> -----Original Message-----
> From: comp-neuro-bounces at neuroinf.org [mailto:comp-neuro-bounces at neuroinf.org 
> ]On Behalf Of james bower
> Sent: Wednesday, August 27, 2008 9:05 AM
> To: CompNeuro List
> Subject: [Comp-neuro] Discussion - Kuhn - and brief comments
>
> A few brief comments -- given that school has started, and I now  
> have to prepare to "influence" the latest next generation.
>
> First a BIG POINT:
>
> Klaus Stiefel:  pre-paradigmatic " What he meant by that is a  
> disagreement about the basic explainanda"
>
> No, Kuhn was focused on process to quote:  "the early developmental  
> stages of most sciences (are) characterized by continual competition  
> between a number of distinct views of nature, each partially derived  
> from, and all roughly compatible with, the dictates of scientific  
> observation and method,  (In pre-paradigmatic science) what  
> differentiates these various schools (is) not one or another failure  
> of method - they are all "scientific" - but what we shall come to  
> call their incommensurable ways of seeing the world and practicing  
> science within it"  (pg 4 The Structure of Scientific Revolution.)    
> If this discussion over the last two months doesn't make it clear  
> that, as a field, we currently have "incommensurate ways of seeing  
> the world and practicing science within it"  I don't know what  
> does.  Kuhn goes on to say:  "Men (sic) whose research is based on  
> shared paradigms are committed to the same rules and standards for  
> scientific practice."  Again, this discussion makes it pretty clear  
> to me that we have not yet reached that point. In fact,  (and I  
> would say reflecting this fact) the kind of discussion we have been  
> having here seldom ever happens as we are content (and being pre- 
> paradigmatic can get away with) agreeing to not discuss what we  
> don't agree on, another characteristic of pre-paradigmatic science  
> -- and the reason I don't mind starting these discussions.
>
> Bryan Bishop:  "There's a few too many layers of folk psychology  
> here,"
>
> I agree, and have characterized all of biology as fundamentally  
> folkloric in nature -- based on story telling, with few real  
> definitions of anything.  Something comp bio (neuro) will, I hope,  
> eventually fix.
>
>
>
> And on to the approaches we don't agree on:
>
> Bryan Bishop:  "I bet it  becomes clear that trying to do "natural  
> language processing" from statistical inferences doesn't get us as  
> much hard science as the brain could provide."
>
> Of course, I agree -- and also agree that this field continues to be  
> distorted by what is essential snake oil we sell to the Department  
> of Defense about how studying the brain will help win wars.  This  
> rather self serving commitment to "neuro-morphic engineering" as it  
> is now called, has been distorting our science for a while.  In the  
> last 8 years even more dramatically.
>
> Mario Negrello:  "I'd say instead that some approaches gather more  
> acolytes, and then overflow others in sheer voluminous quantity,"
>
> Unfortunately, as just noted, very often related to who you are  
> selling the science to (funders) and also, unfortunately, how 'easy'  
> the methods are and therefore how many can jump on the bandwagon  
> without much preparation (or even knowledge of the brain in this  
> case)   -- 20 years studying the realistic model of the Purkinje  
> cell and counting.
>
>
> Bard Ermentrout:  " I suspect that it would be too hard to adjust  
> parameters for realistic models "
>
> Is hard bad?  Or is the brain, in fact, hard?
>
>
> Igor Carron: "The groundwork of theory as you put it has, in nuclear  
> technology, always been a way to acquire and use experimental  
> findings."
>
> And this, in fact, is the value of theory -- not to capture 'truth'  
> as many in comp neuro seem be believe, but to organize experimental  
> studies -- the more the theory is removed from the actual structure  
> of the brain - the more it exists by itself, disconnected from the  
> ability to improve, or more importantly to refute it.
>
>
> Asim Roy:  "a "blank slate" simply implies a network whose  
> connection weights and other parameters have not been set yet -"
>
> And, no such thing in biology, where development doesn't end and  
> learning begins - it is continuous, and development probably  
> recapitulating evolutionary history.  Another reason why the  
> mainstream ANN models make no sense.
>
>
> Asim Roy: "Is there a way in computational neuroscience to verify  
> any of these theories of learning? "
>
> Wrong question.
>
>
> Axel Hutt:  " can (neuro)biology really treat a population of some  
> thousand elements ? "
>
> We will need to figure out how - numerous groups are working on it.
>
>
> Anibalmastobiza:  "cerebellum, usually considered as a center for  
> motor processing and coordination just  as it was for the basal  
> ganglia that now we know that is also involve in cognition"
>
> While I appreciate the support, I have another question for  
> cognitive neuroscientists, how come anything that lights up in a  
> brain scan becomes a "cognitive center"  seems weird to me.
>
>
> Jim
>
>
>
>
>
>
>
>
> ==================================
>
> Dr. James M. Bower Ph.D.
>
> Professor of Computational Neuroscience
>
> Research Imaging Center
> University of Texas Health Science Center -
> -  San Antonio
> 8403 Floyd Curl Drive
> San Antonio Texas  78284-6240
>
> Main Number:  210- 567-8100
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Gary Cottrell 858-534-6640 FAX: 858-534-7029
Computer Science and Engineering 0404
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Email: gary at ucsd.edu
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