The Active Dendritic Tree

We are now prepared to assemble models that are capable of reproducing the great variety of responses, seen in the laboratory, to synaptic input distributed in space and time. This requires only that we add ion channels to our passive dendrite. A combination of the numerical methods of Chapters 4 and 8 will permit us to generate the action potential launched by supra-threshold current injection and to study its propagation down the cell's axon and back up into the dendritic tree, in agreement with the recordings in Figure 9.1. We then build a model for determining the extracellular current induced by such traveling action potentials and study its effect on neighboring cables. We next move on to synaptic initiation of somatic spikes and investigate the role of the NMDA receptor in acknowledging action potential back propagation. We next study the quasi-active cable and its ability to capture the subthreshold response and resonant frequency of the cell. We then investigate synaptic attenuation and integration on our active fork prior to introducing tools for the simulation of arbitrarily branched cells. Finally, we study synaptic integration in the fully branched case.