> > [META: please turn line-wrap on, for each of these responses my own > standards for outgoing mail necessitate that I go through each line and > ensure all quotations are properly formatted...]
I think we're suffering from emacs issues, I'm using elm. > > Iff the brain is not unique in its capability to support intelligence > then all of this can be replaced by some abstract model with the same > basic computational charactaristics but in a very different way. I totally agree. But the genesis of this debate was whether the brain is "complicated" in a non-trivial way. The fact that it is complicated does not mean it cannot be replicated in a different substrate (and like Ben, I think it would be a misapplication of effort to try). > > > The "implementation details" are what tells you how the brain > > functions. > > I don't care _HOW_ it functions, I care about _WHAT_ a given section > accomplishes through its functioning. The nature of neuroscience research doesn't really differentiate between the two at present. In order to understand WHAT a brain part does, we have to understand HOW it, and all structures connected to it function. We need to understand the inputs and the outputs, and that's all HOW. There are people who approach the problem from a purely black-box perspective of course, by giving people memory tests and looking at the pattern of failures. This is extremely interesting work, particularly as regards the types of errors people make while speaking. (http://www.wjh.harvard.edu/~caram/pubs.htm) I don't think it's sufficient, on its own, to figure out the brain without simulteanously looking at the neural data. > > Given that, it should be relatively streight forward to find a > work-alike well, it just isn't. Brains are hard to reverse engineer, and that's basically what you're talking about. > > Failing that, it is still possible to set up a system akin to Creatures > but with a much more powerful engine and wait untill a "good'nuff" > algorithm evolves on its own... It took evolution billions of years with an enormous search space. Obviously we can speed the process. But in the end, you'd end up an equally inscrutable mass of neural tissue. You'd be better off getting yourself a real kid :) > > <rant mode engaged> > I HATE IVORYTOWERISM!!! > IF A BOOK DOESN'T TELL IT LIKE IT IS, IT SHOULD NEVER BE PUBLISHED, EVEN > TO LITTLE CHILDREN!! (Especially not to little children.) My comment was in the context of you saying that the brain is "fantastically simple" and then citing Calvin as a source for your conclusion. I'm saying that books by pop authors are insufficient to draw conclusions from, not that they are useless. His ideas are great, I love his work. > > The brain does have an innate structure in the form of the topology I > mentioned earlier. This topology naturally leads to the development of > functional systems. HOWEVER, there is no law in the *cortex* which > governs what behaviors it will produce (likes, dislikes etc...) these > must be inputed either from the environment or from the subcortical > structures. I disagree with this, but I see where you are coming from. We don't know enough about the cortex to say things like this. The reason that subcortical structures seem more concrete to us, is that they are simpler in design and therefore easier to understand than cortical structures. > Yes, and I don't think those varriations in layers or even connectivity > are at all significant. Ofcourse you want to know which layer is for > input and which layer is for feedback but you don't really worry > yourself about the measurements which are probably a biproduct of having > more neurons in those regions that are heavily connected and not, in > themselves, interesting... The extray layers in the occipital lobe are > probably nothing more than the equivalent of a math coprocessor in a > computer... The addition or deletion of layers is going to drastically change the nature of computations a given bit of cortex performs. > > > I've spent 8 years studying hippocampal anatomy. It is fascinating and > > highly structured in a way the cortex isn't (or its simplicity allows > > us to perceive the structure). Vast volumes of data about its anatomy > > are available and I have read most of it. > > GIMME GIMME GIMME!!! =P I said I read it, I didn't say I could remember all of it :) > > > I( and the rest of the hippocampal community) am at a loss to tell you > > how it functions. > > Do we know what it does? (how its outputs relate to its inputs) Nope. We think it might have to do with spatial navigation in rodents (rats tend to think in terms of 2-D space) and more complex types of memory in higher order critters. Anatomy and neurophysiology seem to suggest it should relate memory to motor actions and behavioral states, but lesion it and animals seem relatively unimpaired in that respect(lesions are a troublesome way to reverse engineer the brain). *throws up hands* There are as many high-level theories of hippocampal function as there are hippocampal researchers, many of which do not overlap at all. It would be a mistake to say there is a general consensus beyond "it helps with memory". > > I would say they are a byproduct of the overall structure (as mentioned > above) and not at all related to any voodoo in the internal structure of > the cortex... There's the crux of our disagreement. You view this cortex as this largely homogenous processor, while I view it as an intricate webwork of "space-shuttle complex" specialized memory systems. To you, the hard part of the brain is figuring out the global scheme. To me, there is no global scheme, it's space-shuttles all the way down. The truth is likely somewhere in between. Obviously there's some degree of commonality between cortical systems for different modalities and the ability for brain structures to compensate for the loss of others indicates the system is certainly not as brittle as I make it out to be. -Brad ------- To unsubscribe, change your address, or temporarily deactivate your subscription, please go to http://v2.listbox.com/member/?[EMAIL PROTECTED]
