C:/Documents and Settings/Ernie/My Documents/Cruncher/Work/JBP paper/Author-generated accepted version/JBP_Bursting_Author-generated_accepted.dvi

We describe a simple conductance-based model neuron that includes intraand extra-cellular ion concentration dynamics and show that this model exhibits periodic bursting. The bursting arises as the fast spiking behavior of the neuron is modulated by the slow oscillatory behavior in the ion concentration variables, and vice versa. By separating these time scales and studying the bifurcation structure of the neuron, we catalog several qualitatively different bursting profiles that are strikingly similar to those seen in experimental preparations. Our work suggests that ion concentration dynamics may play an important role in modulating neuronal excitability in real biological systems.