ENCODING WIDE-FIELD MOTION CHARACTERISTICS IN THE CENTRAL COMPLEX OF THE COCKROACH, BLABERUS DISCOIDALIS by NICHOLAS D. KATHMAN Submitted in partial fulfillment of requirements For the degree of Doctor of Philosophy Advisor: Dr. Roy E. Ritzmann Department of Biology CASE WESTERN RESERVE UNIVERSITY January 2015 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of Nicholas D. Kathman candidate for the Doctor of Philosophy degree*. Committee Chair: Hillel J. Chiel Committee Member: Roy E. Ritzmann Committee Member: Mark A. Willis Committee Member: Jessica L. Fox Committee Member: Daniel W. Wesson Date of Defense: December 5th, 2014 *We also certify that written approval has been obtained for any proprietary material contained therein. ii Copyright © by Nicholas D. Kathman All rights reserved iii Dedication For my dad iv Table of Contents Thesis Summary .......................................................................................................................................... 1 Chapter 1: Introduction ............................................................................................................................. 3 Summary ................................................................................................................................................... 4 Anatomy of the central complex of the insect brain ................................................................................. 5 Structural anatomy ................................................................................................................................ 5 Neurochemical anatomy ....................................................................................................................... 7 Sensory processing in the central complex of the insect brain ................................................................. 9 Polarized light processing ..................................................................................................................... 9 Retinotopic spatial information........................................................................................................... 11 Visual motion in identified cells ......................................................................................................... 12 Mechanreception ................................................................................................................................. 14 Insect vision and visual interneurons of the brain ................................................................................... 15 Insect eyes ........................................................................................................................................... 15 Optic lobes .......................................................................................................................................... 17 Optic flow representing motion .......................................................................................................... 19 Ocelli ................................................................................................................................................... 21 Optomotor response ............................................................................................................................ 22 The central complex and its role in behavior .......................................................................................... 24 Locomotion control ............................................................................................................................. 24 Courtship song and acoustic communication ..................................................................................... 26 Visually guided behaviors................................................................................................................... 27 Basal ganglia homology ...................................................................................................................... 28 My intended contribution to these fields ................................................................................................. 29 Chapter 2: Encoding wide-field motion and direction in the central complex of the cockroach, Blaberus discoidalis .............................................................................................................................. 34 Summary ................................................................................................................................................. 35 Introduction ............................................................................................................................................. 36 Methods ................................................................................................................................................... 38 Animals ............................................................................................................................................... 38 Animal preparation and electrophysiology ......................................................................................... 38 Visual Stimuli ..................................................................................................................................... 40 v Spike sorting and analysis ................................................................................................................... 41 Behavioral testing ............................................................................................................................... 44 Procaine injection ............................................................................................................................... 45 Histology and imaging ........................................................................................................................ 46 Results ..................................................................................................................................................... 47 Silencing neurons of the central complex reduces optomotor response ............................................. 47 Wide-field visual motion and the CX ................................................................................................. 48 Response types to wide-field motion .................................................................................................. 49 Unit response types and directional selectivity ................................................................................... 50 Sensitivity to stimulus temporal frequency ......................................................................................... 51 Responses to wide-field motion with periodic firing .......................................................................... 54 Responses to vertical wide-field motion ............................................................................................. 55 Discussion ............................................................................................................................................... 56 CX neurons convey diverse wide-field motion information ............................................................... 56 Periodic responses to wide-field motion ............................................................................................. 57 Response similarities with motion processing neurons upstream from the CX .................................. 58 The role of CX circuits in optomotor responses ................................................................................. 59 Figures ..................................................................................................................................................... 63 Chapter 3: Ocular dominance of directional responses to wide-field motion in neurons of the central complex of the cockroach, Blaberus discoidalis .................................................................... 72 Summary ................................................................................................................................................. 73 Introduction ............................................................................................................................................. 74 Methods ................................................................................................................................................... 78 Animal preparation ............................................................................................................................. 78 Visual stimuli ...................................................................................................................................... 79 Analysis .............................................................................................................................................. 80 Results ..................................................................................................................................................... 82 General response classifications ......................................................................................................... 82 Temporal response type classifications in binocular conditions ......................................................... 82 Ocular dominance testing ..................................................................................................................