Nature 421, 66–70 (2003).

It has come to our attention that we failed to cite a relevant study1 in our Letter. These authors identified the mechanism of synaptic depression measured at the embryonic chick nucleus magnocellularis to nucleus laminaris synapse as primarily presynaptic, which justifies the synaptic depletion model we used. Furthermore, the narrowing of coincidence detection time windows with EPSP depression as they observed may contribute to the adaptive mechanisms that we described.