Branch-specific clustered parallel fiber input controls dendritic computation in Purkinje cells

Abstract

Most central neurons have intricately branched dendritic trees that integrate massive numbers of synaptic inputs. Intrinsic active mechanisms in dendrites can be heterogenous and be modulated in a branch-specific way. However, it remains poorly understood how heterogenous intrinsic properties contribute to processing of synaptic input. We propose the first computational model of the cerebellar Purkinje cell with dendritic heterogeneity, in which each branch is an individual unit and is characterized by its own set of ion channel conductance densities. When simultaneously activating a cluster of parallel fiber synapses, we measure the peak amplitude of a response (PAR) and observe how changes in P-type calcium channel conductance density shift PAR from a linear one to a bimodal one including dendritic calcium spikes and vice-versa. These changes relate to the morphology of each branch. We show how dendritic calcium spikes propagate and how Kv4 channels block spreading depolarization to nearby branches.