The GABA System in Brain Development

Abstract

All normal or adaptive activity is a result of coordination of excitation and inhibition in the nervous system within and between neuronal subsystems in a particular organism. The underlying principle of information-processing is a coordinated interplay of excitatory and inhibitory influences. Most communication that takes place between receptor and neuron, neuron and neuron, and neuron and effector probably occurs via the presynaptic liberation of substances that have either excitatory or inhibitory influences on postsynaptic membranes (see ref. 1 for review and some pertinent general references). Several known naturally-occurring substances have been implicated as potential excitatory or inhibitory transmitters. Acetylcholine and glutamic and aspartic acids may be excitatory transmitters. γ-Aminobutyric acid (GABA), glycine, the catecholamines, histamine, and serotonin may be inhibitory transmitters. Knowledge of the properties and distributions of the enzymes which form some of these substances and degrade them and of the neural circuits in which they exist is only now becoming available.