4. Axons, dendrites, and synapses

Chapter 2 and chapter 3 considered single neuron models that idealised the nerve cell as a point or patch of cell membrane in which voltage is the same everywhere. However, the classical notion of a neuron is of a specialised cell with a body, an axon, and dendrites [802]. The cell body or soma, contains the nucleus and cytoplasm, the axon extends from the soma and ultimately branches before ending at nerve terminals, and dendrites are branched structures connected to the soma that receive signals from other neurons. Axons and dendrites make contact with each other at axo-dendritic synapses, and dendro-dendritic synapses are also possible. These structures allow neurons to communicate in different ways, and to transmit information to other nerve cells, muscle, or gland cells. In this chapter, we consider idealised mathematical models of these processes and methods for their analysis, which now include a spatial aspect. In later chapters, we make use of these structures and their dynamics to construct model neuronal networks.