Previous studies have shown that in pyramidal neurons the density of the hyperpolarization-activated current Ih increases with distance from the soma and that the presence of Ih results in normalization of the temporal summation of EPSPs, such that the degree of summation is independent of the dendritic location of the inputs. We have recently shown that, in contrast, cerebellar Purkinje neurons exhibit a spatially uniform distribution of Ih (Angelo et al. SFN 2004). The temporal summation as a function of the dendritic location of the input is similar when Ih is present or blocked. Moreover, temporal summation of a train of PSPs in the presence of Ih is linear. This result is remarkable as Ih is a highly non-linear current which clearly participates in shaping of the voltage response. In order to quantitatively understand these results we constructed two models of Ih. The first model is a Hodgkin-Huxley-type model of a non-linear current based on data from dendritic cell-attached recordings from Purkinje ...