How to dismantle a detonator synapse.

Direct electrophysiological evaluation of ion channels in vertebrate presynaptic nerve terminals has been limited to synapses such as the neuromuscular junction and the giant calyx of Held. In this issue of Neuron, Engel and Jonas demonstrate that mossy fiber boutons have specialized voltage-gated Na(+) channels that critically impact upon presynaptic Ca(2+) influx by amplifying terminal invading action potentials.