  Here is proposed a review of the different choices to structure spike trains,
using deterministic metrics. Temporal constraints observed in biological or
computational spike trains are first taken into account. The relation with
existing neural codes (rate coding, rank coding, phase coding, ..) is then
discussed. To which extend the "neural code" contained in spike trains is
related to a metric appears to be a key point, a generalization of the
Victor-Purpura metric family being proposed for temporal constrained causal
spike trains
