The Synaptic Organization of the Brain

The first edition of this book reconciled new findings in synaptic physiology with classic neuron theory. For each of several brain regions such as hippocampus or cerebellum, Shepherd described the major neurons, illustrated their synaptic interrelationships, and diagramed a "basic circuit." This second edition expands to include other brain regions such as the basal ganglia and to communicate new findings, especially regarding neurotransmitter substances. For some brain regions, contrary to the classic view, the dendrite rather than the entire neuron is the basic information-processing unit. The dendrite summates synaptic influences on it and, by way of dendrodendritic synapses, transfers this processed input to another dendrite, without necessarily affecting the potential on the neuronal cell body or axonal membrane. In fact, for the granule cell of the olfactory bulb and the amacrine cell of the retina, dendrodendritic action is the only neuronal communication that can occur; these cells have no axons.