The Activity of Ventral Tegmental Area Dopamine Neurons During Shock Omission Predicts Safety Learning

We studied the role of dopamine [tyrosine hydroxylase (TH)] neurons in the rat ventral tegmental area (VTA) in safety learning. First, we used an AX+/BX-discrimination procedure to establish conditioned stimulus (CS) B as a learned safety signal that passed both summation and retardation tests of conditioned inhibition. Then, we combined this procedure with fiber photometry in TH-Cre rats to study the activity of VTA dopamine neurons during safety learning. We show that whereas footshock is associated with calcium transients in TH neurons across the VTA, shock omission during safety learning is selectively associated with calcium transients in dopamine neurons in the medial but not lateral VTA. Moreover, the magnitude of medial VTA calcium transients during shock omission accurately predicts the amount of safety that is learned and expressed during summation testing. Our findings are consistent with a common medial VTA dopamine mechanism contributing to the learned inhibition of fear in extinction and safety.

Automated summary

This study investigated the role of dopamine neurons in safety learning in the rat ventral tegmental area (VTA). The findings suggest that shock omission during safety learning is selectively associated with calcium transients in dopamine neurons in the medial VTA, and the magnitude of these calcium transients accurately predicts the amount of safety that is learned.