<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Brad, <div>I see your point. In 1962, Herb Simon wrote about levels of analysis and dynamics at each level, and importantly how to think about when it is/is not safe to "ignore" dynamics at some levels: He called it nearly decomposable systems. This is not a neuro/cognitive issue, it is an issue relevant to understanding complex systems in general.</div><div><br></div><div>Mark</div><div><br></div><div><br></div><div>
<!--[if gte mso 9]><xml>
<o:DocumentProperties>
<o:Revision>0</o:Revision>
<o:TotalTime>0</o:TotalTime>
<o:Pages>1</o:Pages>
<o:Words>18</o:Words>
<o:Characters>103</o:Characters>
<o:Company>Columbia University</o:Company>
<o:Lines>1</o:Lines>
<o:Paragraphs>1</o:Paragraphs>
<o:CharactersWithSpaces>120</o:CharactersWithSpaces>
<o:Version>14.0</o:Version>
</o:DocumentProperties>
<o:OfficeDocumentSettings>
<o:AllowPNG/>
</o:OfficeDocumentSettings>
</xml><![endif]-->
<!--[if gte mso 9]><xml>
<w:WordDocument>
<w:View>Normal</w:View>
<w:Zoom>0</w:Zoom>
<w:TrackMoves/>
<w:TrackFormatting/>
<w:PunctuationKerning/>
<w:ValidateAgainstSchemas/>
<w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>
<w:IgnoreMixedContent>false</w:IgnoreMixedContent>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w:DoNotPromoteQF/>
<w:LidThemeOther>EN-US</w:LidThemeOther>
<w:LidThemeAsian>JA</w:LidThemeAsian>
<w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript>
<w:Compatibility>
<w:BreakWrappedTables/>
<w:SnapToGridInCell/>
<w:WrapTextWithPunct/>
<w:UseAsianBreakRules/>
<w:DontGrowAutofit/>
<w:SplitPgBreakAndParaMark/>
<w:EnableOpenTypeKerning/>
<w:DontFlipMirrorIndents/>
<w:OverrideTableStyleHps/>
</w:Compatibility>
<m:mathPr>
<m:mathFont m:val="Cambria Math"/>
<m:brkBin m:val="before"/>
<m:brkBinSub m:val="--"/>
<m:smallFrac m:val="off"/>
<m:dispDef/>
<m:lMargin m:val="0"/>
<m:rMargin m:val="0"/>
<m:defJc m:val="centerGroup"/>
<m:wrapIndent m:val="1440"/>
<m:intLim m:val="subSup"/>
<m:naryLim m:val="undOvr"/>
</m:mathPr></w:WordDocument>
</xml><![endif]--><!--[if gte mso 9]><xml>
<w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true"
DefSemiHidden="true" DefQFormat="false" DefPriority="99"
LatentStyleCount="276">
<w:LsdException Locked="false" Priority="0" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Normal"/>
<w:LsdException Locked="false" Priority="9" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="heading 1"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 5"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 6"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 7"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 8"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 9"/>
<w:LsdException Locked="false" Priority="39" Name="toc 1"/>
<w:LsdException Locked="false" Priority="39" Name="toc 2"/>
<w:LsdException Locked="false" Priority="39" Name="toc 3"/>
<w:LsdException Locked="false" Priority="39" Name="toc 4"/>
<w:LsdException Locked="false" Priority="39" Name="toc 5"/>
<w:LsdException Locked="false" Priority="39" Name="toc 6"/>
<w:LsdException Locked="false" Priority="39" Name="toc 7"/>
<w:LsdException Locked="false" Priority="39" Name="toc 8"/>
<w:LsdException Locked="false" Priority="39" Name="toc 9"/>
<w:LsdException Locked="false" Priority="35" QFormat="true" Name="caption"/>
<w:LsdException Locked="false" Priority="10" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Title"/>
<w:LsdException Locked="false" Priority="1" Name="Default Paragraph Font"/>
<w:LsdException Locked="false" Priority="11" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Subtitle"/>
<w:LsdException Locked="false" Priority="22" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Strong"/>
<w:LsdException Locked="false" Priority="20" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Emphasis"/>
<w:LsdException Locked="false" Priority="59" SemiHidden="false"
UnhideWhenUsed="false" Name="Table Grid"/>
<w:LsdException Locked="false" UnhideWhenUsed="false" Name="Placeholder Text"/>
<w:LsdException Locked="false" Priority="1" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="No Spacing"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 1"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 1"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 1"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 1"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 1"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 1"/>
<w:LsdException Locked="false" UnhideWhenUsed="false" Name="Revision"/>
<w:LsdException Locked="false" Priority="34" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="List Paragraph"/>
<w:LsdException Locked="false" Priority="29" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Quote"/>
<w:LsdException Locked="false" Priority="30" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Intense Quote"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 1"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 1"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 1"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 1"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 1"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 1"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 1"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 1"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 2"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 2"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 2"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 2"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 2"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 2"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 2"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 2"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 2"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 2"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 2"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 2"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 2"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 2"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 3"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 3"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 3"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 3"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 3"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 3"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 3"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 3"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 3"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 3"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 3"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 3"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 3"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 3"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 4"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 4"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 4"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 4"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 4"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 4"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 4"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 4"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 4"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 4"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 4"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 4"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 4"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 4"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 5"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 5"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 5"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 5"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 5"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 5"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 5"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 5"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 5"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 5"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 5"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 5"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 5"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 5"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 6"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 6"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 6"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 6"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 6"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 6"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 6"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 6"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 6"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 6"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 6"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 6"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 6"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 6"/>
<w:LsdException Locked="false" Priority="19" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Subtle Emphasis"/>
<w:LsdException Locked="false" Priority="21" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Intense Emphasis"/>
<w:LsdException Locked="false" Priority="31" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Subtle Reference"/>
<w:LsdException Locked="false" Priority="32" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Intense Reference"/>
<w:LsdException Locked="false" Priority="33" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Book Title"/>
<w:LsdException Locked="false" Priority="37" Name="Bibliography"/>
<w:LsdException Locked="false" Priority="39" QFormat="true" Name="TOC Heading"/>
</w:LatentStyles>
</xml><![endif]-->
<!--[if gte mso 10]>
<style>
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin:0in;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:12.0pt;
font-family:Cambria;
mso-ascii-font-family:Cambria;
mso-ascii-theme-font:minor-latin;
mso-hansi-font-family:Cambria;
mso-hansi-theme-font:minor-latin;}
</style>
<![endif]-->
<!--StartFragment--><span style="font-size:12.0pt;line-height:115%;font-family:
Helvetica;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;
mso-bidi-font-family:Helvetica;mso-ansi-language:EN-US;mso-fareast-language:
EN-US;mso-bidi-language:AR-SA">Simon, H. A. (1962). The architecture of
complexity.<span style="mso-spacerun:yes"> </span><i style="mso-bidi-font-style:
normal">Proceedings of the American Philosophical Society, </i>106(6), 467-482</span><!--EndFragment-->
</div><div><span style="font-size:12.0pt;line-height:115%;font-family:
Helvetica;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;
mso-bidi-font-family:Helvetica;mso-ansi-language:EN-US;mso-fareast-language:
EN-US;mso-bidi-language:AR-SA"><br></span></div><div><span style="font-size:12.0pt;line-height:115%;font-family:
Helvetica;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;
mso-bidi-font-family:Helvetica;mso-ansi-language:EN-US;mso-fareast-language:
EN-US;mso-bidi-language:AR-SA"><br></span></div><div><span style="font-size:12.0pt;line-height:115%;font-family:
Helvetica;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;
mso-bidi-font-family:Helvetica;mso-ansi-language:EN-US;mso-fareast-language:
EN-US;mso-bidi-language:AR-SA"><br></span></div><div><div><div>On Jan 25, 2014, at 9:52 PM, Brad Wyble wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div>Jim, </div><div><br></div><div>Great debate! There are several good points here..</div><div><br></div><div>First, I agree with you that models with tidy, analytical solutions are probably not the ultimate answer, as biology is unlikely to exhibit behavior that coincides with mathematical formalisms that are easy to represent in equations. In fact, I think that seeking such solutions can get in the way of progress in some cases. </div>
<div><br></div><div>I also agree with you that community models are a good idea, and I am not advocating that everyone should build their own model. But I think that we need a hierarchy of such community models at multiple levels of abstraction, with clear ways of translating ideas and constraints from each level to the next. The goal of computational neuroscience is not to build the ultimate model, but to build a shared understanding in the minds of the entire body of neuroscientists with a minimum of communication failures. </div>
<div><br></div><div>Next, I think that you're espousing a purely bottom-up approach to modelling the brain. ( i.e. that if we just build it, understanding will follow from the emergent dynamics). I very much admire your strong position, but I really can't agree with it. I return to the question of how we will even know what the bottom floor is in such an approach You seem to imply in previous emails that it's a channel/cable model, but someone else might argue that we'd have to represent interactions at the atomic level to truly capture the dynamics of the circuit. So if that's the only place to start, how will we ever make serious progress? The computational requirements to simulate even a single neuron at the atomic level on a super cluster is probably a decade away. And once we'd accomplished that, someone might point out a case in which subatomic interactions play a functional role in the neuron and then we've got to wait another 10 years to be able to model a single neuron again? </div>
<div><br></div><div>To me, it really looks like turtles all the way down which means that we have to choose our levels of abstraction with an understanding that there are important dynamics at lower levels that will be missed. However if we build in constraints from the behavior of the system, such abstract models can nevertheless provide a foothold for climbing a bit higher in our understanding. </div>
<div><br></div><div>Is there some reason that you think channels are a sufficient level of detail? (or maybe I've mischaracterized your position)</div><div><br></div><div>-Brad</div><div><br></div><div><br></div><div>
<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sat, Jan 25, 2014 at 7:09 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"><div style="word-wrap:break-word">About to sign off here - as have probably already taken too much bandwidth. (although it has been a long time)<div>
<br><div>But just for final clarity on the point about physics - I am not claiming that the actual tools etc, developed by physics mostly to study non-biological and mostly ‘simpler’ systems (for example, systems were the elements (unlike neurons) aren’t ‘individualized’ - and therefore can be subjected to a certain amount of averaging (ie. thermodynamics), will apply.</div>
<div><br></div><div>But I am suggesting (all be it in an oversimplified way) that the transition from a largely folkloric, philosophically (religiously) driven style of physics, to the physics of today was accomplished in the 15th century by the rejection of the curve fitting, ‘simplified’ and self reflective Ptolemic model of the solar system. (not actually, it turns out for that reason, but because the Ptolemaic model has become too complex and impure - the famous equint point). Instead, Newton, Kepler, etc, further developed a model that actually valued the physical structure of that system, independent of the philosophical, self reflecting previous set of assumptions. I know, I know that this is an oversimplified description of what happened, but, it is very likely that Newtons early (age 19) discovery of what approximated the least squares law in the ‘realistic model’ he had constructed of the earth moon system (where it was no problem and pretty clearly evident that the moon orbited the earth in a regular way), lead in later years to his development of mechanics - which, clearly provided an important "community model” of the sort we completely lack in neuroscience and seem to me continue to try to avoid. </div>
<div><br></div><div>I have offered for years to buy the beer at the CNS meeting if all the laboratories describing yet another model of the hippocampus or the visual cortex would get together to agree on a single model they would all work on. No takers yet. The paper I linked to in my first post describes how that has happened for the Cerebellar Purkinje cell, because of GENESIS and because we didn’t block others from using the model, even to criticize us. However, when I sent that paper recently to a computational neuroscience I heard was getting into Purkinje cell modeling, he wrote back to say he was developing his own model thank you very much.</div>
<div><br></div><div>The proposal that we all be free to build our own models - and everyone is welcome, is EXACTLY the wrong direction. </div><div><br></div><div>We need more than calculous - and although I understand their attractiveness believe me, models that can be solved in close formed solutions are not likely to be particularly useful in biology, where the averaging won’t work in the same way. The relationship between scales is different, lots of things are different - which means the a lot of the tools will have to be different too. And I even agree that some of the tools developed by engineering, where one is actually trying to make things that work, might end up being useful, or even perhaps more useful. However, the transition to paradigmatic science I believe will critically depend on the acceptance of community models (they are the ‘paradigm’), and the models most likely with the most persuasive force as well as the ones mostly likelihood of revealing unexpected functional relationships, are ones that FIRST account for the structure of the brain, and SECOND are used to explore function (rather than what is usually the other way around).</div>
<div><br></div><div>As described in the paper I posted, that is exactly what has happened through long hard work (since 1989) using the Purkinje cell model.</div><div><br></div><div>In the end, unless you are a duelist (which I suspect many actually are, in effect), brain computation involves nothing beyond the nervous system and its physical and physiological structure. Therefore, that structure will be the ultimate reference for how things really work, no matter what level of scale you seek to describe.</div>
<div><br></div><div>From 30 years of effort, I believe even more firmly now than I did back then, that, like Newton and his friends, this is where we should start - figuring out the principles and behavior from the physics of the elements themselves.</div>
<div><br></div><div>You can claim it is impossible - you can claim that models at other levels of abstraction can help, however, in the end ‘the truth’ lies in the circuitry in all its complexity. But you can’t just jump into the complexity, without a synergistic link to models that actually provide insights at the detailed level of the data you seek to collect. </div>
<div><br></div><div>IMHO.</div><div><br></div><div>Jim</div><div><br></div><div>(no ps)</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><div><div class="h5"><br><div><div>
On Jan 25, 2014, at 4:44 PM, Dan Goodman <<a href="mailto:dg.connectionists@thesamovar.net" target="_blank">dg.connectionists@thesamovar.net</a>> wrote:</div><br><blockquote type="cite">The comparison with physics is an interesting one, but we have to remember that neuroscience isn't physics. For a start, neuroscience is clearly much harder than physics in many ways. Linear and separable phenomena are much harder to find in neuroscience, and so both analysing and modelling data is much more difficult. Experimentally, it is much more difficult to control for independent variables in addition to the difficulty of working with living animals.<br>
<br>So although we might be able to learn things from the history of physics - and I tend to agree with Axel Hutt that one of those lessons is to use the simplest possible model rather than trying to include all the biophysical details we know to exist - while neuroscience is in its pre-paradigmatic phase (agreed with Jim Bower on this) I would say we need to try a diverse set of methodological approaches and see what wins. In terms of funding agencies, I think the best thing they could do would be to not insist on any one methodological approach to the exclusion of others.<br>
<br>I also share doubts about the idea that if we collect enough data then interesting results will just pop out. On the other hand, there are some valid hypotheses about brain function that require the collection of large amounts of data. Personally, I think that we need to understand the coordinated behaviour of many neurons to understand how information is encoded and processed in the brain. At present, it's hard to look at enough neurons simultaneously to be very sure of finding this sort of coordinated activity, and this is one of the things that the HBP and BRAIN initiative are aiming at.<br>
<br>Dan<br></blockquote></div><br></div></div><div>
<div style="text-indent:0px;letter-spacing:normal;font-variant:normal;text-align:-webkit-auto;font-style:normal;font-weight:normal;line-height:normal;text-transform:none;white-space:normal;font-family:Helvetica;word-wrap:break-word;word-spacing:0px"><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal"><span style="font-size:14pt;font-family:Verdana;color:rgb(149,0,4)">Dr. James M. Bower Ph.D.</span><u></u><u></u></p><div class="im"><p class="MsoNormal"><span style="font-size:11pt;font-family:'Times New Roman'">Professor of Computational Neurobiology</span></p><p class="MsoNormal"><span style="font-family:'Times New Roman';color:rgb(66,0,168)">Barshop Institute for Longevity and Aging Studies.</span><span style="font-family:'Times New Roman'"><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:'Times New Roman'">15355 Lambda Drive</span><span style="font-family:'Times New Roman'"><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:'Times New Roman'">University of Texas Health Science Center </span><span style="font-family:'Times New Roman'"><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11pt;font-family:'Times New Roman'">San Antonio, Texas 78245</span><span style="font-family:'Times New Roman'"><u></u><u></u></span></p><div><span style="font-family:'Times New Roman'"> </span><br class="webkit-block-placeholder"></div><p class="MsoNormal"><b><span style="font-size:13pt;font-family:'Times New Roman'">Phone: <a href="tel:210%20382%200553" value="+12103820553" target="_blank">210 382 0553</a></span></b><span style="font-family:'Times New Roman'"><u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman'">Email: <a href="mailto:bower@uthscsa.edu" target="_blank">bower@uthscsa.edu</a><u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman'">Web: <a href="http://www.bower-lab.org/" target="_blank">http://www.bower-lab.org</a><u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman'">twitter: superid101<u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman'">linkedin: Jim Bower<u></u><u></u></span></p><div><span style="font-family:'Times New Roman'"> </span><br class="webkit-block-placeholder"></div><p class="MsoNormal"><span style="font-family:'Times New Roman';color:rgb(177,89,19)">CONFIDENTIAL NOTICE:<u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman';color:rgb(177,89,19)">The contents of this email and any attachments to it may be privileged or contain privileged and confidential information. This information is only for the viewing or use of the intended recipient. If you have received this e-mail in error or are not the intended recipient, you are hereby notified that any disclosure, copying, distribution or use of, or the taking of any action in reliance upon, any of the information contained in this e-mail, or<u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman';color:rgb(177,89,19)">any of the attachments to this e-mail, is strictly prohibited and that this e-mail and all of the attachments to this e-mail, if any, must be<u></u><u></u></span></p><p class="MsoNormal"><span style="font-family:'Times New Roman';color:rgb(177,89,19)">immediately returned to the sender or destroyed and, in either case, this e-mail and all attachments to this e-mail must be immediately deleted from your computer without making any copies hereof and any and all hard copies made must be destroyed. If you have received this e-mail in error, please notify the sender by e-mail immediately.</span><span style="font-family:'Times New Roman'"><u></u><u></u></span></p><div><span style="font-family:'Times New Roman'"> </span><br class="webkit-block-placeholder"></div></div></div>
</div>
<br></div></div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div dir="ltr">Brad Wyble<br>Assistant Professor<br>Psychology Department<br>Penn State University<div><br></div><div><a href="http://wyblelab.com/" target="_blank">http://wyblelab.com</a></div>
</div>
</div>
</blockquote></div><br></div></body></html>