Kavli Affiliate: Kevin Bender
| Authors: Mitchell J. Vaughn, Kevin J. Bender and Julie S. Haas
| Summary:
Electrical synapses are present widely across the mammalian brain and are crucial components of active neural circuitry and connectomes. Identification of electrically coupled networks in living tissue has been limited by technical demands of multiplexed recordings, and no dyes, fluorescent reporters, or genetic labels are currently able to fill the gap. Here, we introduce a novel method of identifying and measuring electrical synapses: opto-δL combines focal photostimulation of soma-targeted opsins and a novel method for computing the strength of electrical synapses, based on spike timing, to rapidly measure and map electrically coupled networks in vitro. We measured electrical synapses and characterized coupled networks in mature thalamic reticular nucleus (TRN) and in cortex. We used opto-δL to show that TRN neurons form functional networks that extend as far as 100 μm, and that TRN neurons synapse promiscuously, coupling both matching and disparate genetic subtypes of neurons. Future applications of opto-δL will allow identification and characterization of coupled networks across the brain and enable circuit and systems-level interrogations of the identity and roles of electrical synapses in circuitry, behavior, and cognition.