Functional Insights about Synaptic Inputs to Dendrites

Abstract

This talk briefly reviewed results of earlier computations that simulated synaptic inputs to passive dendritic membrane. Then it reviewed dendritic spines and the possibility that some spine heads might have excitable membrane properties. Because some neurons have dendritic arbors that are studded with hundreds or thousands of spines, computations were used to explore theoretical examples of different synaptic input combinations to both excitable and passive spines. The results demonstrate the possibility of synaptic amplification by action potentials in spine heads, and the possibility of chain reactions between excitable spines. These nonlinear responses could be used for logical processing of inputs in dendritic arbors. Dendro-dendritic synapses were also reviewed briefly; they provide the possibility of graded synaptic interactions between dendritic arbors of different neurons, (without the constraint of all-or-nothing impulses). These examples of modeling and computations based on anatomy and physiology demonstrate both a richness of possibilities and a challenge to future modeling of neurons and networks of neurons. The details below are quite brief; more complete presentations with illustrations are available in the references cited.