STAIN THE BRAIN
With the use of anterograde tracing it is possible to research neuronal projections from the cell body all the way down the neuron towards the synapse. This method is especially handy for researching how neurons deriving from your injected area of interest project towards other areas in the brain. An example of an anterograde tracer is Phaseolus vulgaris leukoagglutinin (PHA-L)
A retrograde tracer is useful for researching projections of neurons from the synapse towards the cell body, so the exact opposite of what the anterograde tracer does. This method is useful for studying how neurons project towards the brain area injected with a retrograde tracer. An example of a retrograde tracer is Cholera Toxin Subunit B (CTb)
E.L. Beverloo, D.G.P. Baltus, A.B. Mulder - University of Amsterdam