There is solid electron microscopic data demonstrating the existence of dopamine (DA) axon
terminals (varicosities) with or without synaptic membrane specializations (junctional
complexes) in many parts of the CNS, and notably in neostriatum and nucleus accumbens.
The dual morphological character of these DA innervations has led to the suggestion that
the meso-telencephalic DA system operates by diffuse (or volume) as well as by classical
synaptic transmission. In the last decade, electrophysiological and neurochemical evidence …