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.