Visualizing selective neural pathways with WGA transgene: combination of neuroanatomy with gene technology.

Functional logic employed by the nervous system for information processing resides mainly in the wiring patterns among specific types of neurons. Therefore, detailed knowledge on neuronal networks is essential for understanding a wide range of brain functions. A powerful and long-awaited method for analyzing the neuronal connectivity patterns would be to deliver tracers selectively to specific types of neurons and at the same time to label transsynaptically their axonal target neurons. For this purpose, we took advantage of a unique property of plant lectin, wheat germ agglutinin (WGA), which has been used as a transsynaptic tracer in classical neuroanatomical studies. We developed a novel genetic strategy that employs WGA cDNA as a transgene, for the visualization of selective and functional neural pathways in the nervous system. In this article, I will introduce several examples of neural pathways visualized with the WGA transgene and discuss about its further refinement and applications.