This book consists of five sections. The first section details methods for analyzing both presynaptic and postsynaptic function and emphasizes the molecular aspects of synapses. It describes ongoing studies of neurotransmitter realease, voltage-sensitive ion channels, and electronic transmission at gap junctions. The second section focuses on the growing menagerie of neurotransmitters: their categorization into chemical families, their relation to ion channels, their modulation by second messenger systems and their role in pharmacologic action. The third section considers the important relationship of transmitter diversity and synaptic types to the behavior of actual cellular networks. The central role of synapses in learning and memory is the subject of the fourth section of the book. The fifth and final section includes modeling studies of the single dendrite as well as novel analyses of synapses in networks.