Sound Localization Behavior in Drosophila The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Batchelor, Alexandra Victoria. 2019. Sound Localization Behavior in Drosophila. Doctoral dissertation, Harvard University, Graduate School of Arts & Sciences. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:41121298 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Sound localization behavior in Drosophila A dissertation presented by Alexandra Victoria Batchelor to The Division of Medical Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Neurobiology Harvard University Cambridge, Massachusetts September 2018 © 2018 Alexandra Victoria Batchelor All rights reserved. Dissertation Advisor: Dr. Rachel I. Wilson Alexandra Victoria Batchelor Sound localization behavior in Drosophila ABSTRACT Drosophila melanogaster hear with their antennae: sound evokes vibration of the distal antennal segment, and this vibration is transduced by specialized mechanoreceptor cells. The left and right antennae vibrate preferentially in response to sounds arising from different azimuthal angles. Therefore, by comparing signals from the two antennae, it should be possible to obtain information about the azimuthal angle of a sound source. However, behavioral evidence of sound localization has not been reported in Drosophila. Here we show that walking Drosophila do indeed turn in response to lateralized sounds. We confirm that this behavior is evoked by vibrations of the distal antennal segment. The rule for turning is different for sounds arriving from different locations: Drosophila turn toward sounds in their front hemifield, but they turn away from sounds in their rear hemifield, and they do not turn at all in response to sounds from 90° or -90°. All these findings can be explained by a simple rule: the fly steers away from the antenna with the larger vibration amplitude. Finally, we show that these behaviors generalize to sound stimuli with diverse spectro- temporal features, and that these behaviors are found in both sexes. Our findings demonstrate the behavioral relevance of the antenna’s directional tuning properties. They also pave the way for investigating the neural implementation of sound localization, as well as the potential roles of sound-guided steering in courtship and exploration. iii TABLE OF CONTENTS Abstract .......................................................................................................................................... iii Table of Contents ........................................................................................................................... iv List of Figures ................................................................................................................................. v List of Abbreviations ..................................................................................................................... vi Acknowledgements ....................................................................................................................... vii Chapter 1: Introduction ................................................................................................................... 1 Why study sound localization in Drosophila? ............................................................................ 1 A review of sound localization in vertebrates ............................................................................. 3 A review of sound localization in invertebrates ........................................................................ 10 Background on the Drosophila auditory system ....................................................................... 16 References ................................................................................................................................. 21 Chapter 2: Sound localization behavior in Drosophila depends on inter-antenna vibration amplitude comparisons ................................................................................................................. 25 Introduction ............................................................................................................................... 25 Materials and Methods .............................................................................................................. 29 Results ....................................................................................................................................... 38 Discussion ................................................................................................................................. 62 References ................................................................................................................................. 68 Chapter 3: Conclusions and Future Directions ............................................................................. 74 A discussion of open questions about sound localization ......................................................... 74 Future behavioral experiments .................................................................................................. 78 References ................................................................................................................................. 81 Appendix A: Supplementary Figures for Chapter 2 ..................................................................... 82 References ................................................................................................................................. 90 iv LIST OF FIGURES Figure 1: Directional tuning of sound-evoked antennal vibrations .............................................. 28 Figure 2: Lateralized sounds elicit phonotaxis as well as acoustic startle .................................... 39 Figure 3: Trial-to-trial variation in phonotaxis behavior. ............................................................. 42 Figure 4: Phonotaxis requires vibration of the distal antennal segment. ...................................... 45 Figure 5: Turning is contralateral to the antenna with larger vibrations. ...................................... 48 Figure 6: Lateralized sounds arriving from the back elicit negative phonotaxis. ......................... 51 Figure 7: Sounds from any of the four cardinal directions elicit no phonotaxis. .......................... 55 Figure 8: Phonotaxis generalizes to sounds with diverse spectro-temporal features. ................... 58 Figure 9: Both males and females display phonotaxis. ................................................................. 61 Figure S1: Speaker calibrations. .................................................................................................. 83 Figure S2: Distribution of forward velocities. .............................................................................. 85 Figure S3: Additional single-trial examples of phonotaxis and acoustic startle behavior. ........... 86 Figure S4: Trial-to-trial variation in forward and lateral velocity are not strongly correlated. .... 88 v LIST OF ABBREVIATIONS ILD – Interaural level difference IPD – Interaural phase difference ITD – Interaural time difference LSO – Lateral superior olive VLVp – Ventral nucleus of the lateral lemniscus MSO – Medial superior olive NL – Nucleus laminaris JONs – Johnston’s Organ Neurons AMMC – Antennal mechanosensory and motor area WED – Wedge vi ACKNOWLEDGEMENTS This work would not have been possible (and the last five years would have been a lot less fun) without the support I’ve had from friends, family and colleagues. Thank you to Rachel for working so hard to support my work in the lab. You have taught me many important lessons: from knowing the importance of ‘good enough’ to how much you can learn from small details in your data. Thank you to the current and former members of the Wilson Lab. It has been such a pleasure to work with all of you. Special thanks to Stephen Holtz for answering thousands of my question - I will dearly miss our Friday Night Comedy chat and coffee breaks. Thanks to Allison Baker for your friendship and mentorship, to Alexandra Moore for late night conversations, to Asa Barth- Maron and Paola Patella for your thoughtful friendship, to Yvette Fisher for your endless enthusiasm, to Jenny Lu for putting up with my chatter, to Michael Marquis for going out of your way to improve lab operations, to Tatsuo Okubo for lots of great conversations about books, to Sasha Rayshubskiy making fun of me, and to Helen Yang for your wise advice. Thank you to the past members of the Wilson Lab (Tony Azevedo, Joe Bell, Mehmet Fisek, Betty Hong, Jamie Jeanne, Wendy Liu, Kathy Nagel, Willie Tobin and John Tuthill) for your mentorship when I didn’t know anything. Thank you to my friends in the Program in Neuroscience. Thank you to Hannah Somhegyi for being an incredible friend and always being there at the right time. Thank you to Stephen Thornquist for your support and encouragement. Comp club was a great learning experience for me, so thank you to the Harvey lab members, Emma Krause and Allie for making it happen. Special thanks to all of the PiN alumni who helped me find a job. vii Thank you to all the members of