Fig. 6: Activation of D1^NAc-VM pathway increases DA release into the NAc and activation of D1^NAc-VP pathway produces opposing effect.

a–f AAV-hSyn-DA2m was infected into the NAc of C57BL/6 mice and an optical fiber was implanted over the NAc to record change of fluorescence of DA sensor DA2m. a Viral infection and representative image of DA2m expression and the location of optical fiber tip in the NAc. b–f Heat map and statistical plot of grouped average DA2m transient for 5% sucrose licking, sucrose pellet consumption, retreat from the novel object in the approaching-retreat test, unpredictable delivery of air puff, and tail suspension (n = 5 mice). g Optical fibers were implanted in the VM/VP and NAc to exert laser stimulation on D1^NAc-VP, D1^NAc-VM, or D2^NAc-VP projection and record DA2m signal in the NAc simultaneously. AAV₉-EF1α-DIO-hChR2-mCherry and AAV-hSyn-DA2m were infected into the NAc of D1-Cre or D2-Cre mice. h Representative images of DA2m expression and fiber tip location in NAc, and ChR2 labeled axons in the VP and VM. Left: Statistical graph of group average GCaMP responses aligned to optical stimulation (473 nm, 20 Hz, 1 s) of D1^NAc-VM (i), D1^NAc-VP (j), or D2^NAc-VP (k) projection. Right: bar graph of peak response to optical stimulation [Mann-Whitney U test: i Control n = 5, ChrimsonR n = 6, Z = 2.739, P = 0.0043; j Control n = 5, ChR2 n = 6, Z = -2.739, P = 0.0043; k Control n = 6, ChR2 n = 6, Z = -2.882, P = 0.0022;] **P < 0.01. l Working model illustrating mesolimbic D1^NAc-VM and D1^NAc-VP pathways cooperatively control dopamine balance and reward-aversion state.