Dynamic Adaptation in Fly Motion Vision Virginia L. Flanagin München 2006 Dynamic Adaptation in Fly Motion Vision Virginia L. Flanagin Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.) der Fakultät für Biologie der Ludwig-Maximilians-Universität München Angefertigt am Max-Planck-Institüt für Neurobiologie, Abteilung ‚Neuronale Informationsverarbeitung’ vorgelegt von Virginia L. Flanagin aus Chicago, IL USA München, den 01. Juni 2006 3 Ehrenwörtliche Versicherung Ich versichere hiermit ehrenwörtlich, dass die Dissertation von mir selbständig, ohne unerlaubte Beihilfe angefertigt ist. Martinsried, den……………………… ………………………………………… Erklärung Hiermit erkläre ich, dass ich mich anderweitig einer Doktorprüfung ohne Erfolg nicht unterzogen habe. Martinsried, den…………………….. …………………………………………. Erstgutachter: Professor Dr. Alexander Borst Zweitgutachter: Professor Dr. Benedikt Grothe Tag der mündlichen Prüfung: 20. Juli 2006 4 Table of Contents TABLE OF CONTENTS .........................................................................................................................5 TABLE OF FIGURES.................................................................................................................................7 ABBREVIATIONS ....................................................................................................................................8 ABSTRACT...........................................................................................................................................10 1 INTRODUCTION.........................................................................................................................12 FLY VISUAL SYSTEM.............................................................................................................................13 Photoreceptors ...............................................................................................................................15 Lamina...........................................................................................................................................18 Medulla..........................................................................................................................................19 The lobula complex .........................................................................................................................21 Lobula plate tangential cells ............................................................................................................21 ELEMENTARY MOTION DETECTION........................................................................................................24 General Principles ..........................................................................................................................24 Gradient-type detector.....................................................................................................................25 The Reichardt Detector Model .........................................................................................................27 Evidence for the Reichardt Detector .................................................................................................30 ADAPTATION .......................................................................................................................................32 Efficient information transfer ...........................................................................................................33 Automatic adaptation ......................................................................................................................36 H1-cell and adaptation....................................................................................................................38 The time course of adaptation ..........................................................................................................41 JUSTIFICATION.....................................................................................................................................43 2 METHODS ...................................................................................................................................45 EXPERIMENTS......................................................................................................................................45 Preparation ....................................................................................................................................45 Electrical Recording .......................................................................................................................47 Visual Stimulation...........................................................................................................................49 DATA ANALYSIS ..................................................................................................................................54 Stimulus-Response Curves ...............................................................................................................55 Dynamic Gain ................................................................................................................................55 Cross-Correlation...........................................................................................................................56 MODELING ..........................................................................................................................................56 Visual Pattern.................................................................................................................................57 Motion Detector..............................................................................................................................58 TABLE OF EQUIPMENT AND SUPPLIERS....................................................................................................59 3 RESULTS .....................................................................................................................................61 DEPENDENCE ON STIMULUS STATISTICS.................................................................................................62 H1-cell firing properties ..................................................................................................................62 Stimulus-Response Function ............................................................................................................64 Dynamic Gain ................................................................................................................................67 5 Cross-correlations ..........................................................................................................................69 DEPENDENCE ON VISUAL PATTERN........................................................................................................71 TIME COURSE OF ADAPTATION..............................................................................................................77 4 DISCUSSION................................................................................................................................83 GENERALITY .......................................................................................................................................84 Examples of automatic adaptation....................................................................................................84 Adaptation mechanisms in the Reichardt detector..............................................................................85 Adaptation of individual neurons and the Reichardt detector ..............................................................88 EFFICIENCY .........................................................................................................................................89 Efficient representations of correlations............................................................................................92 Ambiguity.......................................................................................................................................93 DYNAMIC ADAPTATION IN MOTION DETECTION .......................................................................................94 VISUAL PATTERNS AND NATURAL SCENES ..............................................................................................97 FUNCTIONALITY IN THE FLY VISUAL SYSTEM ..........................................................................................99 Physiology of motion detection.........................................................................................................99 H1-cell functionality......................................................................................................................101 LPTCs network connectivity...........................................................................................................102 CONCLUDING REMARKS......................................................................................................................103 5 REFERENCES ...........................................................................................................................105 6 ACKNOWLEDGEMENTS .........................................................................................................111 7 CURRICULUM VITAE..............................................................................................................112 6 Table of Figures