資源描述:
《Optimizing the vertebrate vestibular semicircular canal could we balance any better》由會(huì)員上傳分享,免費(fèi)在線閱讀,更多相關(guān)內(nèi)容在行業(yè)資料-天天文庫(kù)。
1、Optimizingthevertebratevestibularsemicircularcanal:couldwebalanceanybetter?ToddM.SquiresDepartmentsofPhysicsandAppliedandComputationalMathematics,CaliforniaInstituteofTechnology114-36,Pasadena,CA91125(Dated:February2,2008)The?uid-?lledsemicircularcanals(SCCs)ofthev
2、estibularsystemareusedbyallvertebratestosenseangularrotation.Despitemassesspanningsevendecades,allmammalianSCCsarenearlythesamesize.WeproposethattheSCCrepresentsasensoryorganthatevolutionhas‘optimallydesigned’.FourgeometricparametersareusedtocharacterizetheSCC,and‘
3、buildingmaterials’ofgivenphysicalpropertiesareassumed.IdentifyingphysicalandphysiologicalconstraintsonSCCoperation,we?ndthatthemostsensitiveSCChasdimensionsconsistentwithavailabledata.0Simplephysicalprinciplesandscalingargumentshave10beenremarkablye?ectiveinunderst
4、andingorganismic?1andevolutionarypropertiesoftheanimalkingdom[1].10d(mm)Sensoryorgans,whichtransducephysicalstimuliinto?2neuralsignals,areparticularlywell-suitedforphysical10?2?10123451010101010101010analysis.Thebiophysicsofthecochlea,forexample,has1beenthefocusofm
5、uchrecentstudy[2].10Herewefocusonadi?erentinner-earorgan:the?uid-?lledsemicircularcanals(SCCs)thateachoftheroughlyR(mm)01045,000vertebratespeciesemploystomechanicallysense?2?10123451010101010101010rotation[3,4].Rotationsensationisobviouslyimpera-Mass(kg)tiveforbala
6、nce,butalsoplaysanequallyimportantroleinvision.TheneuraloutputoftheSCCsfeedsdirectlyFIG.1:MeasuredvaluesofRanddformammals[6,7].totheoculomotorsystem,causingare?exivemotionofDespitesevendecadesofmassvariation,variationsinRandtheeyesthatcompensatesforheadmotion.Thisa
7、llowsdarelimitedtoaboutonedecade.Solid(dashed)horizon-tallinesre?ect‘optimal’(‘tolerant’)SCCdimensions(12-youtoreadthisarticleevenwhileshakingyourhead,15).Roughmeasurementsofcandtformammals[13]revealataskwhichwouldbemuchmoredi?cultifthearticlet~0.15?0.44mmandc~0.17
8、?0.5mm(c.f.optimalitselfwereshaken.c=0.12,t=0.12.)Previously,westudied‘top-shelfvertigo’,amechan-icaldisorderofthehumanSCC[5].Here,weaddressarath