Genesis of bursting activity: Role of inhibitory constraints on persistent Na+ currents

Some neurons express a plateau of spike activity greatly outlasting a stimulus, whereas others do not. This difference could be due to differential expression of ion channels (e.g., persistent Na+, and Ca2+) or similar expression of channels that differ in their properties. We compared three Aplysia neurons with varying capacity to generate plateau potentials: B51 with self-terminating plateaus, B64 with plateau potentials that do not self-terminate, and the regular spiking neuron B8. Our results indicate the three neurons expressed outward currents I A and I D, voltage-gated Ca2+ currents I CaL and I CaR, and persistent inward I NaP. The most notable difference observed was a larger I A, I D, and I KCa currents in B8, and the plateau generating B64 did not express I KCa. Computational models suggest outward currents suppress and temporally constrain the plateau potential and that inward Ca2+ currents suppress plateau potentials when coupled with I KCa. ### Competing Interest Statement The authors have declared no competing interest.