ELECTRO-PHYSIOLOGICAL EVIDENCE FOR AN INPUT FROM THE ANTERIOR OLFACTORY NUCLEUS TO SUBSTANTIA NIGRA

Extracellular recordings were made from spontaneously active neurons in the substantia nigra (SN) region of halothane-anesthetized rats. Histologically identified neurons recorded in the dopamine (DA)-rich zona compacta (ZC) region could be distinguished from those in the zona reticulata (ZR) region on the basis of action potential duration, firing frequency, and responsiveness to intravenously administered DA agonist and antagonist drugs. Electrical stimulation of the ipsilateral anterior olfactory nucleus evoked complex excitatory and inhibitory responses in the majority (69%) of the ZC cells studied; but only in 2 of 30 cells from the ZR. Electrical stimuli delivered to the limbs were effective in influencing the firing rate of only a few cells. These results indicate that a connection exists, possibly via the medial forebrain bundle, between olfactory systems and the DA-containing cells of the SN. © 1979.