Dendritic subunits determined by dendritic morphology

A theoretical framework is presented in which arbitrarily branched dendriti c structures with nonhomogeneous membrane properties and nonuniform geometr y can be transformed into an equivalent unbranched structure (equivalent ca ble). Rall's equivalent cylinder is seen to be one part of the equivalent c able in the special case of dendrites satisfying the Rall criteria. The rel ation between the branched dendrite and its equivalent unbranched represent ation is uniquely defined by an invertible mapping that connects configurat ions of inputs on the branched structure with those on the unbranched struc ture, and conversely. This mapping provides a new definition of dendritic s ubunit and provides a mechanism for characterizing local and nonlocal signa l processing within dendritic structures.