Focal recording of synaptic currents from single boutons at the Drosophila neuromuscular junction

The Drosophila larval neuromuscular junction (NMJ) shares many structural and functional similarities to synapses in other animals, including humans. These include the basic feature of synaptic transmission, as well as the molecular mechanisms regulating the synaptic vesicle cycle. Because of its large size, easy accessibility, and the well-characterized genetics, the fly NMJ remains an excellent model system for dissecting the cellular and molecular mechanisms of synaptic transmission. Focal recording is an extracellular method designed for the study of synaptic activity of one or a few synaptic boutons rather than the ensemble activity of all of the boutons, as occurs with intracellular recording or the two-electrode voltage-clamp (TEVC) method. This is a useful technique for investigating the properties of different motor neurons that innervate the same muscle, applying statistical analysis to discrete synaptic events, and investigating the heterogeneity of synaptic release properties among boutons.