Gerald Edelman and The Remembered Present

This video of Gerald Edelman (Nobel prizewinner, director of NSI, and promoter of the Theory of Neuronal Group Selection, or "Neural Darwinism") giving a presentation to an audience of IBM engineers contains a description of his newest work with the Darwin robots. He and his research team have recently implemented a hippocampal model in Darwin X (including layers for entorhinal cortex, dentate gyrus, CA1 & CA3), and trained it on a robot-adapted version of the water maze task. In this version of the task, the robot is turned on inside a room with 4 walls, each of which has a unique visual stimulus. At around 42 minutes into the video, you can see the robot train on the water maze task, and ultimately learn to find the "hidden platform," which in this version of the task is a wall with red pieces of paper on it.

Unfortunately, the next high point in the lecture actually doesn't come until the Q&A session, during which the following rather uncomfortable exchange takes place between Edelman and a member of the audience:

Q: "[I'm] confused at your distinction between consciousness and science, or programs, or whatever. Because, I may be a reductionist at heart - I'm an electrical engineer - but, it seems to me, there is an underlying machine that executes some set of actions. You can write programs that are stochastic in nature. You can have randomness as part of that. What is the distinction?"

Edelman: "Let me ask you a question. Do you think that evolution is a Turing machine?"

[awkward silence.]

Q: "Do I think that evolution is a Turing machine?"

Edelman: "Yes. Think on that a while. In fact, [...] there are no programs - there is a set of variations. There is a set of unpredicted events which then make selections, which then themselves change their repertoire..."

Q: "But as many people who build genetic algorithms will say, I can write a computer simulation that will simulate many of the effects that underlie evolution."

Edelman: "Yes you can, but what you can't do, is do it ab initio without you involving yourself. That is to say, that is what happens during evolution, and I believe that is what happens in your brain. But yes there is a discussable point here: after the event has been described, you can always write a program..."

Q: "Let me take it a different way. You say the brain is an adaptable thing, but there has to be some underlying process ... a process over which there are some remarkable similarities between the behaviors of all the resulting systems."

Edelman: "Sure, and that's because we have value systems acting as constraints, and phenotypes acting as constraints. If I were a violinist, and someone offered to replace my right arm - my bow arm - with the most remarkable tentacle of an octopus, that's even more flexible than my arm, I'd reject it. Because, in fact, the joints are responsible for doing staccato.

So ... all of what you're saying is true; after you know what's going on you can write a program. The challenge is: can you write a program - and I don't take it that genetic algorithms are a program for evoluion - to explain the evolutionary features of the system. Because I don't believe that evolution is a Turing machine. For example, if it is, why don't you write a program and tell me what we'll look like in a million years.

There are these uncertainties in these systems, implicit in the variation. From a biological point of view, that's not the challenge. That's what Darwin did to add to physics. Physicists in general have done magnificent things, but they haven't really dealt with this point of Darwin: namely, the variation is the substrate... What is amazing is that from the bottom up [evolution] actually takes variation, and from variation [evolution] makes consistency towards species. That is the essential idea, and I don't think we have in fact made a program that does anything except reflect known properties after the event.

There is an interesting problem here... if there is dice tossing, in the event, can the thing remain a Turing machine? [...] I believe, if there is dice tossing at the fundamental level, you can't have what we call a Turing machine. Turing was a genius, and he started to talk about other kinds of machines - Oracle machines, and so on - but didn't spell them out. Alas."

And a few minutes later:

Edelman: "Suppose we did understand everything about how your brain works ... So, do you think [it] would not work by beliefs, desires, and intentions? [...] Do you believe that your illusion of time, namely of your movement from the past, to the present, to the future, is actually a correct descriptor, when in fact the past and future are concepts, and only the remembered present is the one you are experiencing right now?"

Related Posts:
Binding through Synchrony: Proof from Developmental Robotics


Blogger The Neurocritic said...

Have you ever tried to read Neural Darwinism or The Remembered Present? Here are some choice quotes.

"Consciousness is thus a property of morphology or, more precisely, of certain morphological structures in a given phenotype. [NOTE: here he means cell adhesion molecules and substrate adhesion molecules, as outlined in Topobiology.] It is based on their material and molecular order, on the developmental interaction of the phenotype with objects and events in an econiche, and on the continually updated relation to immediate perceptual categories of remembered self-nonself categories that are based on value."

--Gerald Edelman, The Remembered Present, page 263

Now aren't you glad you understand consciousness?

"Psychological functions such as perceptual categorization, memory, and learning are not properties of molecules, of synapses, or even of small numbers of neurons, nor are they general faculties independent of phenotypic change. Instead, they reflect the concerted workings in each phenotype of the motor and sensory ensembles correlating neuronal group selection events occurring in a rich and distributed fashion over global mappings."

--ibid, page 58

Now aren't you glad you understand psychological functions?

7/24/2006 05:47:00 PM  
Blogger Chris Chatham said...

Ugh. It's beautiful language, but I really can't say that I understand what he's trying to say.

It was pretty entertaining to watch the audience member try to respond to a "ricochet question," phrased in similarly obscure language...

7/24/2006 06:03:00 PM  

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