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Title: Supraspinal activity patterns underpinning locomotor diversity in larval zebrafish
Author: Yen Na Lau, Joanna
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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How do supraspinal circuits produce the diversity of locomotor outputs needed for an animal’s survival? To answer this question, I study the reticulospinal (RS) system of larval zebrafish, as these cells provide the main source of descending motor control. I combine two-photon calcium imaging of RS neurons with high-speed behavioural tracking to study RS activity across a range of kinematically distinct swim types. Examination of reticulospinal recruitment across different swim types has revealed unique, but partially overlapping activity patterns, suggesting that some cells encode kinematics common to multiple swim types, while others encode kinematics which are characteristic of a specific swim type. By developing regression-based encoding models which describe a cell’s activity using low-level tail kinematics, we identify “kinematic modules”. These modules contain cells with similar kinematic encoding and thus represent the core combinations of kinematic features encoded by RS activity. I find that laser ablation of cells within a module produce specific kinematic deficits without affecting shared elements of locomotion. This data suggest a circuit architecture where kinematic modules can be differentially combined to produce locomotor diversity through the context-specific recruitment of particular groups of RS neurons. I also describe a novel preparation for the imaging of fluorescent activity indicators in larval zebrafish using an acousto-optic lens microscope. This methodology allows for rapid 3D point scanning of the entire reticulospinal complex during visual stimulus presentation and behavioural tracking. The improved temporal resolution and sampling across the whole population provides an opportunity to examine the relative timing of activity between reticulospinal neurons.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available