Extracellular Recording of Electrical Activity in the Drosophila Central Nervous System

Place a transected central nervous system, or CNS, of a Drosophila larva inside a recording chamber filled with saline solution.

The transected CNS includes the ventral ganglia and descending peripheral nerves.

Place a suction electrode at the posterior end of the transected CNS. Connect the chamber to a grounding wire to reduce background noise.

Apply negative pressure to draw a peripheral nerve into the electrode and initiate extracellular recording of the nerve activity.

Monitor the spontaneous generation of action potentials by neurons over time, termed the baseline firing frequency, and allow it to stabilize.

Add a solvent as a control. Record the activity to ensure the firing frequency remains consistent with the baseline.

Introduce the target test agent dissolved in the solvent and record the firing frequency.

An increase in frequency exhibits the agent's excitatory effect, whereas a decrease in frequency indicates an inhibitory effect.

To begin, first, pull the glass pipette electrode from borosilicate glass capillaries to a resistance of 5 to 15 megaohms. Insert the transected CNS into a wax chamber containing 200 microliters of saline. Clamp an uncoated insect pin with an