An ionic model for Type 3 firing in neurons (Clay et al 2008)
Some neurons fire only once in response to a sustained depolarizing current pulse, type 3 behavior. One example, surprisingly, is the squid giant axon. The Hodgkin-Huxley (HH) model of this preparation fires repetitively for these conditions – type 2, a result that is not observed experimentally as shown in the above paper. Changing one parameter of their model of IK is sufficient to mimic the result.
Clay JR, Paydarfar D, Forger DB (2008) A simple modification of the Hodgkin and Huxley equations explains type 3 excitability in squid giant axons. J R Soc Interface 5.29:1421-8 [PubMed]