into multi-protein complexes that are then conveyed by transient interactions with more rapidly moving cargoes moving in fast axonal transport. An analogy is the difference in transport rates between local and express subway trains. Though both types of train travel at similar velocities between stations, the local train takes much longer to reach the end of the line because it stops at every station whereas the express makes only a few stops on the way. Anterograde transport Anterograde (also called "orthograde") transport is movement of molecules/organelles outward, from the cell body (also called soma) to the synapse or cell membrane. The anterograde movement of individual cargoes (in transport vesicles) of both fast and slow components along the microtubule is mediated by kinesins. Several kinesins have been implicated in slow transport, though the mechanism for generating the "pauses" in the transit of slow component cargoes is still unknown. There are two classes of slow anterograde transport: slow component a (SCa) that carries mainly microtubules and neurofilaments at 0.1-1 millimeters per day, and slow component b (SCb) that carries over 200 diverse proteins and actin at a rate of up to 6 millimeters per day. The slow component b, which also carries actin, are transported at a rate of 2-3 millimeters per day in retinal cell axons. During reactivation from latency, the herpes simplex virus (HSV) enters its lytic cycle, and uses anterograde transport mechanisms to migrate from dorsal root ganglia neurons to the skin or mucosa that it subsequently affects. A cargo-receptor for anterograde transport motors, the kinesins, has been identified as the amyloid precursor protein (APP), the parent protein that produces the senile plaques found in Alzheimer's disease. A 15-amino acid peptide in the cytoplasmic carboxyl terminus of APP binds with high affinity to conventional kinesin-1 and mediates transport of exogenous cargo in the giant axon of the squid. Manganese, a contrast agent for T1-weighted MRI, travels by anterograde transport after stereotaxic injection into the brain of experimental animals and thereby reveals circuitry by whole brain MR imaging in living animals, as pioneered by Robia Pautler, Elaine Bearer and Russ Jacobs. Studies in kinesin-light chain-1 knockout mice revealed that Mn2+ travels by kinesin-based transport in the optic nerve and in the brain. Transport in both hippocampal projections and in the optic nerve also depends on APP. Transport from hippocampus to forebrain is decreased in aging and destination is altered by