Channelrhodopsin2 mediated stimulation of synaptic potentials at Drosophila neuromuscular junctions

The Drosophila larval neuromuscular preparation has proven to be a useful tool for studying synaptic physiology. Currently, the only means available to evoke excitatory junctional potentials (EJPs) in this preparation involves the use of suction electrodes. In both research and teaching labs, students often have difficulty maneuvering and manipulating this type of stimulating electrode. In the present work, we show how to remotely stimulate synaptic potentials at the larval NMJ without the use of suction electrodes. By expressing channelrhodopsin2 (ChR2) in Drosophila motor neurons using the GAL4-UAS system, and making minor changes to a basic electrophysiology rig, we were able to reliably evoke EJPs with pulses of blue light. This technique could be of particular use in neurophysiology teaching labs where student rig practice time and resources are limited.