Response of Gap Junction-Coupled Dendrites: A Sum-Over-Trips Approach

Abstract

Dendrites form the major components of neurons. They are complex branching structures that receive and process thousands of synaptic inputs from other neurons. The impulse response function for branched dendritic trees can be calculated using a so-called sum-over-trips approach. In this chapter we extend this formalism to treat networks of dendritic trees connected via dendro-dendritic gap junctions. To illustrate the usefulness of this extended formalism for understanding how gap junctions can contribute to signal integration in neural networks, we consider how they affect somatic voltages in a simple two neuron network with gap junction coupling between distal dendrites. We find that proximal input on one cell can strongly innervate the soma of that cell though the spread of charge to the gap junction-coupled cell is weak. In contrast distal inputs on one cell weakly innervate the soma of that cell though charge can spread effectively to the gap junction-coupled cell.