tasks,providinganotherwindowto preven- We uncovereda signal processingmethod single,highly conservedembryonicstage in tion throughpsychomotortraining(2). Fi- to isolatethis noisefromthe restof the pupil the vertebrates(1). Principallybecauseof our nally,with the use of methodsthat buildon responseand foundthat the noise variance conclusions regardingthe inaccuraciesof those of Manucaand Savit and the team at had a significantclinical applicationin that drawingsmadeby the 19th-centurynaturalthe Universityof Michigan,we have found it couldaccurately(90%confidence)distin- ist-philosopherErnstHaeckel,ourpaperrethat morethan halfof epilepticcrisescan be guish individualswith attentiondeficit dis- ceived considerablecoveragein the popular anticipatedby a briefwindowand are ame- order(narcoleptics)fromnormal(control) and scientificpress(2), includingan article nable to electricalinterventionof the kind individuals(2). In memoryexperiments,we by ElizabethPennisi ("Haeckel'sembryos: describedin Glanz'sarticle(3). also observedthat neural noise has a dra- Fraudrediscovered," ResearchNews,5 Sept., Michel Le Van Quyen matic impacton cognitiveperformance. We p. 1435). Regrettably, in the resultingdebate JacquesMartinerie believe that the reticularactivatingsystem overHaeckelandthe realityof the vertebrate FranciscoJ. Varela controls the noise we measureand, if so, "phylotypic" stage,whatweregardasoneof the CognitiveNeuroscience Laboratory (LENA) there should be more clinical applications mainimplicationsof our resultsfor contemCentreNationalde la forattentiondeficitdisordersin the future. porarystudiesof the developmentalbasisof Recherche Scientifique (CNRS), WilliamD. O'Neill evolutionarychange has been largelyoverHopitalde la Salpetriere, Department of Bioengineering,looked. 75651 ParisCedex13, France The idea that there is an identicalemUniversity of Illinois, E-mail:
[email protected] Chicago,IL 60607, USA bryonic stage (the phylotypicstage) comE-mail:
[email protected] to all vertebratesimpliesthat changes References in developmentthat underliethe considerReferences able variationin adultmorphologyof these 1. M. Le Van Quyen, J. Martinerie, C. Adam, H. animalsappearonly later in ontogeny. In Schuster, F. Varela, Physica E56, 3401 (1997). 1. S. F. Stanton and L. Stark, IEEE Trans. Biol. Eng. this sense, the concept of the phylotypic 2. M. Le Van Quyen etal., Neuroreport8, 1703(1997). 13, 140 (1966). stageis an explicitstatement,or hypothesis, 2. W. D. O'Neill etal., J. Sleep Res. 5, 265 (1997). 3. C. Adam etal., Epilepsia38 (suppl. 3), 217 (1977); J. Martinerie et al., in preparation. aboutthe temporaldeploymentof evolutionU arychangesin development.Yetwe showthat Glanz quotes one investigator to the effect at leastsome significantdifferencesin adult that neural noise does not have clinical apHaeckel's Embryos morphology,involvingcharactersas fundaplication as yet. But three decades ago, it mentalto the vertebratebodyplan as limbs was discovered that the pupil motor re- A recentpaperthatwe authoredwithseveral and somites,beginto appearbefore,and are sponse has a neural noise component (1). colleagueschallengesthe ideathat thereis a apparentat, the putative phylotypicstage. These and similarobservations(3) seriously diminish the validity and applicabilityof the phylotypicstage concept for the vertebrates.More important,they remindus of the potentialsignificanceof earlierdevelopmentalevents to the determinationof animal form, and that these too are frequent targetsof evolutionaryperturbation. James Hanken Department of Environmental, Population, andOrganismic Biology, w2t2m; University of Colorado, Atlast! Boulder,CO 80309-0334, USA E-mail:
[email protected] assay Analternative Michael K. Richardson to met your St. George'sHospitalMedicalSchool, LondonSW]7 ORE, researchbudget. UnitedKingdom
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References 1. M. K. Richardson et al., Anat. Embryol. 196, 91
(1997). 2. N. Hawkes, The Times (London), 12 Aug. 1997, p. 14; B. K. Hall, Trends Ecol. Evol. 12, 461 (1997). 3. M. K. Richardson et al., Development, in press.
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Secretion of Thiols and Disulfide Bond Formation: Retraction
In our report"Cysteineand glutathionesecretionin responseto proteindisulfidebond
