Population and single dopamine neuron activity during classical conditioning

We trained naive or trained mice to associate odor cues with outcome (water, air puff or no outcome), and recorded dopamine cell body activity in the vetral tegmental area (VTA), dopamine axon activity in the ventral striatum (VS) or dopamine release in VS with optic fiber fluorometry (photometry). In different set of mice, single dopamine neuron activiy was recorded with 2-photon microscope. In some of these mice, we reversed odor-outcome contingency so that an odor that was associated with no outcome or air puff became associated with water reward. Licking pattern was also recorded.