Electroporation is an efficient method of transferring charged macromolecules into living cells in order to study their morphology, function, and connectivity within neuronal networks. Labeling cells with fluorophore-coupled macromolecules can be used to trace projections of whole neuronal ensembles, as well as the fine morphology of single cells. Here, we present a protocol to visualize pre- and postsynaptic components of a sensory relay synapse in the brain, using the olfactory system of Xenopus laevis tadpoles as a model. We apply bulk electroporation to trace projections of receptor neurons from the nose to the brain, and single cell electroporation to visualize the morphology of their synaptic target cells, the mitral-tufted cells. Labeling the receptor neurons with a calcium-sensitive dye allows us to record stimulus-induced presynaptic input to the dendrites of the postsynaptic cells via functional calcium imaging.
Weiss, L., Offner, T., Hassenklöver, T., & Manzini, I. (2018). Dye electroporation and imaging of calcium signaling in Xenopus nervous system. In Methods in Molecular Biology (Vol. 1865, pp. 217–231). Humana Press Inc. https://doi.org/10.1007/978-1-4939-8784-9_15