The brain's complexity depends largely on the variety of its neuronal cell types, but what further functional heterogeneity exists within each class of neurons is still poorly documented. Focusing on the olfactory system, Troy Margrie and colleagues now report that mitral cells belonging to the same glomerulus — and therefore receiving input from one common odorant receptor — express similar levels of the HCN2 ion channel subunit, and thus present similar neuronal excitability. Mitral cells engaged in brain circuits linked to other glomeruli express different biophysical profiles, suggesting that intrinsic diversity among neurons of a given morphological class may reflect functional adaptations of local circuits to the subtly distinct information they process.
