Alexander Calhoun
BME PhD Defense Presentation

Date: 2025-11-12
Time: 2:00 pm
Location / Meeting Link: EBB CHOA Seminar Room; https://gatech.zoom.us/j/3505476534

Committee Members:
Hang Lu, PhD (Advisor); Robert Butera, PhD (Co-advisor); Gordon Berman, PhD; Shu Jia, PhD; Patrick McGrath, PhD; Astrid Prinz, PhD


Title: Light-sheet microscopy and software tools for functional imaging of the C. elegans nervous system

Abstract:
Functional fluorescence imaging of small, transparent organisms like C. elegans has proven to be a powerful tool for understanding the development and function of intact nervous systems at the cellular level. This approach can provide a detailed view of how sensory information is detected, encoded, and integrated to drive behavior, particularly when combined with microfluidic tools that enable precise manipulation of sensory cues. Light-sheet fluorescence microscopy has a number of advantages for functional imaging, including efficient axial sectioning, reduced photobleaching, and capacity for high acquisition speed compared to confocal methods. However, many light-sheet microscope configurations with properties ideal for functional imaging geometrically limit sample access in a way that precludes use with microfluidics. In this thesis work, I designed and constructed an open-top light-sheet microscope that uses simplified inverted water immersion coupled with tunable lens remote focusing under model predictive control to achieve high-speed, multichannel 3D imaging of specimens in conventional microfluidics. I also developed a new actor-based software approach for user-responsive system control and image processing tools for tracking the worm body surface during movement and deformation. With this system, we recorded calcium activity from C. elegans neurons at camera-limited volume rates up to 20 Hz, observed whole-brain response to chemical stimulation at single-cell resolution, and discovered new evidence of compartmentalized dendritic response of the PVD neuron to harsh-touch mechanical stimulation.