The neural mechanisms of persistent inhibition in the DNLL of the gerbil (Meriones unguiculatus) [Elektronische Ressource] / vorgelegt von Bernadette T. Saunier Rebori

Bernadette T. Saunier Rebori

Sujets

• Biologie

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2008
• Nombre de lectures: 19
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

THENEURALMECHANISMSOFPERSISTENT
INHIBITIONINTHEDNLLOFTHEGERBIL
(Meriones unguiculatus)


Dissertation
zurErlangungdesGradeseinesDoktors
derNaturwissenschaften

derFakultätfürBiologie
derLudwigMaximiliansUniversitätMünchen





vorgelegtvon
BernadetteT.SaunierRebori
München,February2008

























Erstgutachter : Prof. Dr. Benedikt Grothe

Zweitgutachter : Prof. Dr. Axel Borst

Tag d. mündl. Prüfung : 31. März 2008

ERKLÄRUNG

Ich versichere,daβ ich meineDissertation selbstständig,ohneunerlaubteHilfe
angefertigt, und mich dabei keiner anderen als der von mir ausdrücklich
bezeichnetenHilfenundQuellenbedienthabe.
DieDissertationwurdeinderjetzigenoderähnlichenFormbeikeineranderen
Hochschule eingereicht und hat noch keinen sonstigen Prüfungszwecken
gedient.




_____________________ _______________________
(Ort,Datum) (BernadetteT.SaunierRebori)
















(…) antes de descubrir, en descubrirnos; antes
de modelar la Naturaleza, en modelarnos.
Forjarnos un cerebro fuerte, un cerebro original,
exclusivamente nuestro: he aquí la labor
preliminarabsolutamenteinexcusable.

Reglas y consejos sobre la investigación
científica. Los tónicos de la voluntad.
Santiago Ramón y Cajal.

TABLEOFCONTENTS

ACKNOWLEDMENTS...........................................................................................1

1.ABSTRACT .......................................................................................................3

2.INTRODUCTION................................................................................................5
2.1Soundlocalizationinthemammalianbrain................................................5
2.2BinauralprocessingintheDNLL................................................................7
2.3Theprecedenceeffectandechosuppression .........................................10
2.4Synaptictransmission...............................................................................13
2.5TheMongoliangerbilasananimalmodel ...............................................17
2.6Scopeofthestudy....................................................................................18

3.MATERIALSANDMETHODS........................................................................21
3.1Invivorecordings .....................................................................................21
3.1.1Animalpreparation...........................................................................21
3.1.2Stereotaticprocedure.......................................................................21
3.1.3Recordingprocedure .......................................................................22
3.1.4Acousticstimuli ................................................................................23
3.1.5Dataanalysis....................................................................................24
3.1.6Histology ..........................................................................................25
3.2Invitrorecordings .....................................................................................27
3.2.1Brainslicepreparation .....................................................................27
3.2.2Wholecellrecordings.......................................................................31
3.2.3Stimulationofsynapticinputs ..........................................................32
3.2.4Dataanalysis....................................................................................32
3.2.5Statisticalanalysis............................................................................33
3.3Appendix...................................................................................................34
3.3.1Histology ..........................................................................................34
3.3.1.1.Ringersolutioncontainingheparin(foranimalperfusion) ...........34
3.3.1.2.Nisslstaining................................................................................34
I

3.3.2Dataanalysis....................................................................................35
3.3.2.1.Convert.pl.....................................................................................35
3.3.2.2.Lastpeak......................................................................................36
3.3.2.3.Allpeaks.......................................................................................37
3.3.2.4.bpc_Mini.xop................................................................................38

4.RESULTS ........................................................................................................39
4.1BinauralresponsepropertiesofDNLLneurons.......................................39
4.2Invitrophysiology.....................................................................................42
4.2.1 The contralateral DNLL provides the long lasting GABAergic
inhibition ....................................................................................................42
4.2.2 The decay time constant of GABAergic IPSCs can explain the PI
foundinvivoandinvitro ...........................................................................45
4.2.3 The stimulation strength increase in the IPSC kinetics suggest a
possibleroleofspilloverinDNLLlonglastinginhibition...........................46
4.2.4 Presynaptic mechanisms might be involved in extending synaptic
inhibitioninDNLLneurons........................................................................51
4.2.5TheapplicationofalowaffinityGABA receptorantagonistsuggestA
theinvolvementofextrasynapticreceptorsinprolongingsynapticinhibition
inDNLL .....................................................................................................56
4.2.6BlockingGABAclearanceprolongedtheIPSCkinetics..................63
4.2.7ReducingreleaseprobabilitydecreasedtheIPSCskinetics...........68
4.2.8GlycinergicinputsontoDNLLneurons ............................................74

5.DISCUSSION...................................................................................................83
5.1PersistentinhibitionintheDNLLoftheMongoliangerbil.........................83
5.2DNLLcelltypesandtheirphysiologicalpropertiesinvitro.......................85
5.3ThesourceofPIintheDNLL...................................................................87
5.4SpilloverprolongssynapticinhibitionintheDNLL ...................................89
5.5AsynchronousreleaseinDNLLprincipalneuronscontributestoPIathigh
frequencyactivitylevels..................................................................................97
5.6GlycinergicinputsontoDNLLneurons.....................................................99
II


6.CONCLUSIONS.............................................................................................101

7.REFERENCES...............................................................................................105

LISTOFABBREVIATIONS ..............................................................................117

CURRICULUMVITAE……………………………………………………………..121
III

INDEXOFTABLESANDFIGURES

Fig.2.1.TheDNLLcircuitry…………………………………………………………..8
Fig.2.2.Theprecedenceeffect…………………………………………….……….11
Fig. 3.2.1. Schematic illustration of DNLL location in the mammalian brain
………………………………………………………………………………….………27
Table3.2.1.ExtracellularsolutionsforslicingandrecordingDNLL………….…28
Table3.2.2.Internalsolutionsforvoltageandcurrentclamprecordings…….....29
Table3.2.3.Drugsandconcentrationsusedduringtheexperiments…………...30
Fig.4.1.PIevokedinvivobyipsilateralstimulation……………………………….40
Fig.4.2.PIevokedinvitrobystimulationoftheCommissureofProbst………...44
Fig.4.3.DecaytimeofevokedIPSCsinvitromimicsPIinvivo……………….…46
Fig.4.4.GABAergicIPSCskineticsdependencyonstimulationstrength…….…49
Fig.4.5.DepressioncurvesofGABAergicIPSCsafterastimulationtrain……...53
Fig.4.6.FrequencydependencyofGABAergicIPSCsafterastimulationtrain
………………………………………………………………………………………….54
Fig.4.7.Effectof100IMTPMPAontheIPSCskinet ics………………………..57
Fig. 4.8. Effect of 200 IM TPMPA on the kinetics of the last IPSC after
stimulationtrain……………………………………………………………………...59
Fig.4.9.Effectof200IMTPMPAonthekineticsof asingleevokedIPSC..…61
Fig.4.10..EffectofalowconcentrationofahighaffinityGABA antagonistonA
theIPSCskinetics…………………………………………………………………...63
Fig.4.11.EffectofNO711ontheIPSCsdecay………………………………….64
Fig.4.12.LowconcentrationsofNNC711prolongsIPSCskinetics…………..66
Fig.4.13.ReducingtheextracellularcalciumreducestheIPSCskinetics…....69
Fig.4.14.ThereductiononextracelluarcalciumreducesGABAspillover…….71
Fig.4.15.CadmiuminducesareductionofGABAspillover……………………73
Fig.4.16.DNLLneuronsreceivebothGABAandglycinergicinputs……….…76
Fig.4.17.DependencyofglycinergicIPSCskineticsonstimulationstrength...79
Fig.4.18.FrequencydependencyofglycinergicIPSCs…………...……………81
IVAknowledments
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