Figure 1.

Imaging striatal dopamine axons during decisions requiring integration of sensory evidence and reward value. A, Task schematic. Mice were head-fixed in front of a screen displaying grating stimuli on the left or right side. Mice were rewarded with water for turning a steering wheel to bring the grating stimulus into the center. B, Task timeline. C, Reward size changed in blocks of 100–500 trials with larger reward available on either right (orange) or left (brown) correct choices. D, Left, Average psychometric curves of an example mouse (12 sessions), showing probability of choosing the stimulus on the right as a function of contrast on the left (L) or right (R), in the two asymmetric reward conditions (orange vs brown). Right, Population psychometric curves. E, Schematic of AAV-Flex-GCaMP6 injection into the midbrain of DAT-Cre mice and implantation of optic fiber above the VS or DMS. F, Left, Histologic slide showing GCaMP expression (green) and position of optic fiber in the VS of an example animal. Right, Estimated position of fiber optic tips. G, The same as F but for DMS.