Genetic Labeling of Synapses

Abstract

A major challenge in neuroscience is to unravel how the synaptic contacts between neurons give rise to brain circuits. A number of techniques have been developed to visualize the synaptic organization of neurons. In this chapter, we focus on genetic methods to mark specific types of synapses so that synaptic sites can be visualized throughout the entire dendritic or axonal arbor of single neurons. Genetic synaptic labeling can be achieved by cell-type-specific viral or transgenic delivery of synaptic proteins tagged by fluorescent proteins. Sparse genetic labeling of neurons permits semiautomated quantification of the distribution and densities of selected types of synapses in segregated domains of the axonal and dendritic trees. These approaches can reduce the complexity and ambiguity of attributing synaptic sites to unravel principles of the synaptic organization of identified neuronal types in the circuit.

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