The crossing of the synaptic cleft is a vital difference between the anterograde tracers and the dye fillers used for morphological reconstruction.
These techniques initially relied upon the direct physical injection of various visualizable tracer molecules (e.g. green fluorescent protein, lipophylic dyes or radioactively tagged amino acids) into the brain.
[1] Over the recent years viral vectors have been developed and implemented as anterograde tracers to identify the target regions of projecting neurons.
[3][4] Alternatively strategies are transsynaptic anterograde tracers, which can cross the synaptic cleft, labeling multiple neurons within a pathway.
[citation needed] Recently manganese-enhanced magnetic resonance imaging (MEMRI) has been used to trace functional circuits in living brains, as pioneered by Russ Jacobs,[5] Robia Paultler,[6] Alan Koretsky and Elaine Bearer.
[8] Statistical parametric mapping of Mn accumulation in time-lapse images provides detailed information not only about neuronal circuitry but also about the dynamics of transport within them, and the location of distal connections.
After endocytosis, the low pH inside the vesicle strips the envelope of the virion after which the virus is ready to be transported to the cell body.