Chapter 5 - Electrical Synapses

Abstract

The scientists who first investigated the mechanisms of synaptic transmission debated whether neurons communicated with one another using electrical signals or chemical signals. On one hand, electrophysiologists wondered why an action potential would propagate to the end of the axon with an amplitude sufficient to carry it directly on to the postsynaptic cell, only to instead be terminated at the axon terminal and trigger the release of a chemical that excites the postsynaptic cell. On the other hand, pharmacologists wondered why the nerve terminal would release a chemical that can excite the postsynaptic cell, if that chemical were not used to mediate communication between cells. As we now know, they were both right! While chemical synapses may be the most abundant in the nervous system, the electrical synapses in the adult mammalian central nervous system are critical for some of the complex functions it can perform. The use of both types of synapses (electrical and chemical) provides a rich diversity of mechanisms neurons can use to signal to one another.