ABSTRACT
The study of synapses, including how they initially form and later reorganize, has a long history-one often marked by lively debates and strong differences of opinion. As noted in previous chapters, neurobiologists in the late 1800s debated whether neurons communicated through a syncytial network or through connections between individual cells. Evidence ultimately demonstrated that neurons communicated through small spaces-connections now termed synapses. In the first half of the twentieth century, scientists engaged in another debate, this one regarding whether the communication at synapses occurred primarily through chemical or electrical signals. These differing opinions were often referred to as the “war of the soups and the sparks,” with the “soups” referring to chemical signals and the “sparks” to electrical signals. As scientists tested the two hypotheses, it was eventually determined that the majority of synapses utilize chemical signals in the form of neurotransmitters to mediate neural communication. Chapters 9 and 10 therefore focus on the development of structures associated with chemical synapses. While most of what is currently known about synaptic development comes from studies of the more prevalent chemical synapses, mechanisms regulating the development of electrical synapses, such as those formed by gap junctions, also remain an active area of study, and in some synaptic locations chemical and electrical signals work together to optimize neuronal communication.
