Extracting multi-neuron and dendritic activities from a freely behaving Drosophila larva

We study the decision-making process in Drosophila larva by simultaneously recording behavior and neural activity in a freely moving larva. We have developed a two-photon microscope that can reliably track and record activity from single or two nearby neurons [1]. To expand to multi-neuron recording, we volumetrically scan the vicinity of the tracked neuron, obtaining calcium imaging recordings from all neuron cell bodies, axons, and dendrites in the local neural circuit. The brain of a freely behaving larva undergoes significant motion and deformation, which presents new challenges for image analysis and neural signal extraction. We have developed a new analysis pipeline in 3D, combining new and existing tools in image processing to overcome these challenges. Calcium images are registered for both rigid and non-rigid motion, then corrected for spatial and temporal intensity fluctuations caused by motion, and neural activities are extracted from the processed images using a region of interest (ROI)-based method. We use this pipeline to examine the A27h premotor neurons of freely moving larvae, extracting activities from both cell bodies and the surrounding dendritic network.

[1]  D. Karagyozov, M. M. Skanata, A. Lesar, M. Gershow. Cell Reports. doi: 10.1016/j.celrep.2018.10.013