Leakage Currents
The known presence of GABAA receptors on mormyrid ELL granular cells provides a strong rationale for including a GABAA dependent Cl- leak current, although the nonspecific GABAA source has yet to be identified in mormyrid ELL granular cells. Accordingly, slow ionic currents mediated by nonspecific mixed-affinity ion channels and a GABAA dependent Cl- leak, previously identified in rat cerebellar granule cells (D’Angelo et al., 2001), were included in the model. This nonspecific leakage was set at a current density of 5.68 X 10-5 S/cm2, with a reversal potential of —59mV. The GABAA mediated leak was set at a current density of 2.17 X 10-5 S/cm2, with a reversal potential of —65mV (close to the Cl- reversal potential of —69mV). Both leakage currents were taken from the earlier model of rat cerebellar granule cells (D’Angelo et al., 2001) again with the assumption of homology between the two granule-type cell populations. Although neither leakage current exerted strong effects on model behavior in D’Angelo et al. (2001), both were included here for completeness.