Analyzing the Prey-Evoked Neuronal Activity in a Transgenic Zebrafish Larva

After culturing paramecia and anesthetizing a zebrafish larva according to the text protocol, place the larva into 2% low-melting-point agarose, and immediately remove any excess agarose so that the surface of the agarose looks slightly convex. Using a dissecting needle, quickly orient the larva in an upright position.

Then, using a surgical knife, make a few small cuts in the agarose to remove the agarose around the zebrafish head, which makes space for the paramecium to swim. Carefully remove the residual agarose by gently pouring system water on the chamber. Next, put one paramecium in the recording chamber to serve as a visual stimulus.

Then, place the recording chamber under an epifluorescence microscope equipped with a scientific CMOS camera and select a 2.5x objective lens. Start the image acquisition application for the equipped camera. Click Sequence Pane and select Hard Disk Record on the pane. In the Scan Settings section, set the frame count to 900 or any other total frame number desired.

In the Capture pane, set the Exposure Time at 30 milliseconds and Binning to 2 by 2. Click Live on the capture pane to locate the larva in the camera view and focus, and then click Stop Live and click the Start button. Save the movie in .cxd format and analyze the data according to the text protocol.