In neuroscience, anterograde tracing is a research method that is used to trace axonal projections from their source (the cell body, or soma) to their point of termination (the synapse). A hallmark of anterograde tracing is the labeling of the presynaptic and the postsynaptic neuron(s). The crossing of the synaptic cleft is a vital difference between the anterograde tracers and the dye fillers used for morphological reconstruction. The complementary technique is retrograde tracing, which is used to trace neural connections from their termination to their source (i.e. synapse to cell body).[1] Both the anterograde and retrograde tracing techniques are based on the visualization of the biological process of axonal transport.
The anterograde and retrograde tracing techniques allow the detailed descriptions of neuronal projections from a single neuron or a defined population of neurons to their various targets throughout the nervous system.[2] These techniques allow the "mapping" of connections between neurons in a particular structure (e.g. the eye) and the target neurons in the brain. Much of what is currently known about connectional neuroanatomy was discovered through the use of the anterograde and retrograde tracing techniques.[1]