Dale's theory assumes that the neuron acts as a metabolic unit, where the process that occurs in the cell can affect all parts of the neuron. This has unfortunately turned literature into a principle that "one cell releases only one neurotransmitter".

Until recently, this has affected many neuroscientists to consider the suspicion that conventional neurotransmitters can share their release from neurons. It is now clear that "one neuron, one neurotransmitter" is the exception rather than the norm.

The aim of this book is to gather available evidence, presented by authors who have discovered and studied the coexistence or co-release of several pairs of neurotransmitters, in several neural networks. It will provide a timely overview of the mechanism of neural communication that is likely to attract increased attention from the nerve community..