Fifty years ago, Hodgkin and Huxley carried out their classic experiments on the ionic basis of the action potential, and explained the properties of membrane currents by invoking the existence of 'gating particles' that move under the influence of an electric field. Few imagined that their vision would spawn one of the fastest developing areas of the neurosciences — the study of ion channels. And even fewer predicted that within five decades, the field would change so profoundly. What started as a strictly neurophysiological question quickly became a biophysical one, focused on establishing the nature of those gating particles, and determining their physical and kinetic properties. Later, the cloning of a plethora of channels brought about a new change, and the problem migrated from the biophysical to the molecular-biological arena, largely dominated by the mutational and chimeric analysis of every possible channel. Now the Zeitgeist has changed again: the crystallographic analysis of both voltage- and ligand-gated channels has placed the field in the realm of the purest structural biology.

In this issue, we recognize this astonishing progress by featuring a series of articles on the three channel families that epitomize it best — glutamate receptors (page 91), potassium channels (page 115) and nicotinic acetylcholine receptors (page 102). Some might argue that there is little neuroscience left in the study of ion channels when the key experiments are carried out at the synchrotron and their interpretation involves atomic coordinates instead of picoamperes. But the truth is that crystallographic analysis has opened our eyes to new principles of channel function, and is beginning to answer questions that neuroscientists have been asking for a long time. So let's embrace this new Zeitgeist as we have done over the past fifty years. The biggest surprises are yet to come.