Chapter Overview

In this chapter we look at the nervous system in microcosm, focusing on the individual nerve cell and especially on the individual synapse. Researchers have come to understand some of the complex electrochemical mechanisms that not only permit communication from one nerve cell to the next but also allow communication to be modified depending on circumstances. It is this mechanism that permits higher organisms—in particular, human beings—to go beyond reflexes and engage in the highly complex behaviors required for survival and success in complicated physical and social environments.

To understand these mechanisms we consider first the nature of the nerve cell membrane and the factors and forces influencing the movement of ions across it. We then look at how the activity of multiple synapses, situated at thousands of different positions on the cell membrane of a receiving neuron, are summed and integrated to cause the nerve cell to fire and release neurotransmitters, affecting other neurons. We then consider the types of neurotransmitters, the processes by which they bind to receptors, and additional factors that influence their effects. Finally, we will examine how some aspects of learning and memory are beginning to be understood in terms of processes at the neuronal level.

By looking at the processes occurring at the molecular and cellular levels we can get some idea of the kind of decision making that goes on in the nervous system as a whole. As we will see, these processes allow the system to code, or represent, enormous complexity.