[New neuronal tracers and their combined use]

Neuroanatomical tract-tracing methods are powerful tools for the study of brain circuits. The use of axonal tracers has become very popular during the past few years. Tract-tracing allows us to study the way in which two or more brain areas are connected and can be used to obtain detailed data on the processing of information within a particular area. The recent development of protocols combining several tracers has resulted in an important breakthrough. Although technically very demanding, these multitracer procedures have become state of the art protocols in several laboratories, rendering a broad range of possibilities for their application in Neurobiology.