Electrophysiological evidence for non-dopaminergic mesocortical and mesolimbic neurons in the rat.

The neurons located in the ventromedial tegmentum (VMT) and projecting either to the frontal cortex, to the septum or to the nucleus accumbens were identified by the antidromic activation method in normal rats and in animals whose dopaminergic (DA) systems had been previously lesioned by microinjections of 6-hydroxydopamine (6-OHDA). Two groups of VMT neurons innervating each structure could be distinguished. The first group (group S) are slow conducting neurons whose number is reduced in 6-OHDA lesioned rats and which may correspond to A10 DA neurons. The second group (group F) are fast conducting neurons which are resistant to 6-OHDA treatment and therefore probably non-DA VMT cells.