Cover Caption

About the cover: Selective activation of α4* nAChRs reveals two receptor subtypes mediating nicotine-induced activation of VTA dopaminergic neurons. Action potential firing from a VTA dopaminergic neuron in a slice from an animal harboring a mutation in the α4 nicotinic receptor subunit that alters nicotine potency. Nicotine and various compounds were applied as indicated. Representative recordings of spike firing corresponding to individual time points are shown. A summary of changes in the neuronal firing is also shown. See article by Liu et al. on page 541 of this issue.