<div dir="ltr"><div>Hi Jim,</div><div><br></div>Focusing too much on the details is risky in and of itself. Optimal compression requires a balance, and we can't compute what that balance is (all models are wrong). One thing we can say for sure is that we should err on the side of simplicity, and adding detail to theories before simpler explanations have failed is not Ockham's heuristic. That said it's still in the space of a Big Data fuzzy science approach, where we throw as much data from as many levels of analysis as we can come up with into a big pot and then construct a theory. The thing to keep in mind is that when we start pruning this model most of the details are going to disappear, because almost all of them are irrelevant. Indeed, the size of the description that includes all the details is almost infinite, whereas the length of the description that explains almost all the variance is extremely short, especially in comparison. This is why Ockham's razor is a good heuristic. It helps prevent us from wasting time on unnecessary details by suggesting that we only inquire as to the details once our existing simpler theory has failed to work.<div>
<br></div><div>Brian</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Mar 19, 2014 at 12:42 PM, james bower <span dir="ltr"><<a href="mailto:bower@uthscsa.edu" target="_blank">bower@uthscsa.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Actually, the previous statement is only true in its most abstract form -which in that form also applies to the heart, the kidney and trees too. So not sure what use that is. (trees used cellular based communication to react to predation by insects - and at least mine look like they are in pain when they do so).<br>
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the further statement about similar developmental processes for cortical like brain structures is also only true in its most abstract sense. In particular, the cerebellum has a quite unique form of cortical development (very different from the frontal cortical structures. cell migration patterns, the way cellular components get connected, as well as general timing - all of which are almost certainly important to its function. The cerebellum, for example, largely develops entirely postnatally in most mammals. It is also important to note that cerebellar development is also considerably better understood than is the case for cerebral cortex.<br>
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Again, as I have argued many times before - in biology (perhaps unfortunately) the devil (and therefore the computation) is in the details. Gloss over them at your risk.<br>
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Jim<br>
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On Mar 19, 2014, at 12:50 PM, Juyang Weng <<a href="mailto:weng@cse.msu.edu">weng@cse.msu.edu</a>> wrote:<br>
<br>
> Mike,<br>
><br>
> Yes, they are very different in the signals they receive and process after at least several months' development prenatally, but this is<br>
> not a sufficiently deep causality for us to truly understand how the brain works. Cerebral cortex, hippocampus and cerebellum are all very similar in the mechanisms that enable them to develop into what they are, prenatally and postnatally.<br>
><br>
> An intuitive way to think of this deeper causality is: Development is cell-based. The same set of cell properties enables cells to migrate, connect and form cerebral cortex, hippocampus and cerebellum while each cell taking signals from other cells.<br>
><br>
> -John<br>
><br>
> On 3/14/14 3:40 PM, Michael Arbib wrote:<br>
>> At 11:17 AM 3/14/2014, Juyang Weng wrote:<br>
>>> The brain uses a single architecture to do all brain functions we are aware of! It uses the same architecture to do vision, audition, motor, reasoning, decision making, motivation (including pain avoidance and pleasure seeking, novelty seeking, higher emotion, etc.).<br>
>><br>
>> Gosh -- and I thought cerebral cortex, hippocampus and cerebellum were very different from each other.<br>
>><br>
><br>
> --<br>
> --<br>
> Juyang (John) Weng, Professor<br>
> Department of Computer Science and Engineering<br>
> MSU Cognitive Science Program and MSU Neuroscience Program<br>
> 428 S Shaw Ln Rm 3115<br>
> Michigan State University<br>
> East Lansing, MI 48824 USA<br>
> Tel: <a href="tel:517-353-4388" value="+15173534388">517-353-4388</a><br>
> Fax: <a href="tel:517-432-1061" value="+15174321061">517-432-1061</a><br>
> Email: <a href="mailto:weng@cse.msu.edu">weng@cse.msu.edu</a><br>
> URL: <a href="http://www.cse.msu.edu/~weng/" target="_blank">http://www.cse.msu.edu/~weng/</a><br>
> ----------------------------------------------<br>
><br>
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