Whole-cell in vivo patch-clamp recordings in the Drosophila brain

Whole-cell patch-clamp recordings provide exceptional access to spiking and synaptic neural activity. This method has been applied to neurons in the central nervous system of Drosophila and allows researchers the opportunity to study the function of their neurons of interest within the context of native circuits in a genetically tractable model system. In this protocol, we describe the technique for in vivo whole-cell patch-clamp recordings in a preparation which exposes neurons in the fly brain. We also offer technical suggestions and discuss some of the challenges encountered in recording from single neurons in the fly brain. Neurons are patched following routine recording protocols for whole-cell patch clamp. At the physiology rig, additional cleaning of the brain is performed to allow easy access to the neurons, and the cells can be filled with a diffusible dye during recordings, to examine the morphology of the recorded cell post hoc. In the electrophysiology rig used for Drosophila patch-clamp recordings, the microscope stage has been removed, so that the recording platform instead rests on a ring stand support that is magnetically fixed to the table. Manipulators and stimulus delivery are also in fixed locations, whereas the microscope sits on an x-y translation stage.