Regulation of working memory switches from striatal dopamine D2-receptor to D1-receptor neurons under high cognitive load
Fig 6
Optogenetic inhibition of DMS dopamine signaling rescue WM impairment induced by D1R-neuron activation.
A Schematic illustrating the viral injection of DIO-ChR2-EYFP or DIO-EYFP, along with the implantation of optic fiber in DMS, and the injection of mTH-ArchT-mCherry or mTH-mCherry, with optic fiber implantation in VTA/SNc of Drd1-Cre (+) mice. B Left: Representative images displaying ChR2 expression (green), ArchT fibers from VTA/SNc (red), alongside TH staining (magenta) and DAPI (blue) in DMS; Right: Representative images in VTA/SNc showing ArchT expression (red), ChR2 projections in SNR (green), TH staining (magenta) and DAPI (blue) in VTA/SNc. ArchT was selectively expressed in TH-positive dopaminergic neurons. C During the 60 s “delay” phase, photoactivation of DMS D1R-neurons with 470 nm laser severely impaired WM performance (Group 1 ‘DMS EYFP + VTA/SNc mCherry’ vs. Group 3 ‘DMS ChR2 + VTA/SNc ArchT’: RM two-way ANOVA, main effect, F1, 14 = 15.92, ##p < 0.01; interaction, F3, 24 = 0.9179, p > 0.05; Fisher’s LSD post-hoc comparisons, Day 2, *p < 0.05, Day 3, **p < 0.01; Group 1 ‘DMS EYFP + VTA/SNc mCherry’ vs. Group 2 ‘DMS ChR2 + VTA/SNc mCherry’: RM two-way ANOVA, main effect, F1, 16 = 20.22, ###p < 0.001; interaction, F3, 48 = 0.5375, p > 0.05; Fisher’s LSD post-hoc comparisons, Day 2, *p < 0.05, Day 3, **p < 0.01, Day 4, *p < 0.05). D During the “delay” phase, photoinhibition of dopaminergic neurons in VTA/SNc (red prismatic) with 560 nm laser effectively rescued D1R-neuron activation-induced WM impairment, yielding performance comparable to the control group (black circle) (Group 2 ‘DMS ChR2 + VTA/SNc mCherry’ vs. Group 3 ‘DMS ChR2 + VTA/SNc ArchT’: RM two-way ANOVA, main effect, F1, 14 = 5.024, #p < 0.05; interaction, F2, 48 = 1.485, p > 0.05; Fisher’s LSD post-hoc comparisons, Day 7, **p < 0.01). E In Group 3, dual stimulation significantly improved WM performance compared to single stimulation (red column). Additionally, it demonstrated notable enhancements over Group 2, with no significant difference with Group 1 (One-way ANOVA for comparisons among the three groups; Paired-samples t test for group 3’s comparisons between single and dual stimulation; Group 1, n = 9, Group 2, n = 9, Group 3, n = 7). F Without interventions, WM performance among the three groups was comparable, showing no significant differences. G The viral injection strategy was similar to that described in panel A. Twin-core optic fibers were implanted into DMS to activate D1R-neurons and inhibit DMS dopaminergic terminals, either respectively or simultaneously. H Left: Representative images showing ChR2 expression (green), ArchT fibers from VTA/SNc (red), TH staining (magenta), and DAPI (blue) in DMS; Right: Representative images VTA/SNc showing ArchT expression (red), ChR2 fibers in SNR from DMS (green), TH staining (magenta), and DAPI (blue). ArchT was selectively expressed in TH-positive dopaminergic neurons VTA/SNc. I WM performances of the three groups were comparable without manipulations during the learning stage (Day 1–4). J During the 60 s “delay” phase, photoactivation of DMS D1R-neurons with 470 nm laser severely impaired WM performance (Group 1 ‘DMS EYFP + VTA/SNc mCherry’ vs. Group 3 ‘DMS ChR2 + VTA/SNc ArchT’: RM two-way ANOVA, main effect, F1, 56 = 14.20, ## p < 0.01; interaction, F3, 56 = 1.123, p > 0.05; Fisher’s LSD post-hoc comparisons, Day 6, **p < 0.01, Day 7, *p < 0.05). K During the “delay” phase, photoinhibition of DMS dopaminergic terminals with 560 nm laser (red prismatic) successfully rescued WM impairment induced by D1R-neuron activation, yielding performance comparable to the control group (black circle) (Group 3 vs. Group 1: RM two-way ANOVA, main effect, F1, 14 = 4.751, p > 0.05, interaction, F2, 28 = 0.2166, p > 0.05; Group 3 vs. Group 2 ‘DMS ChR2 + VTA/SNc mCherry’: RM two-way ANOVA, main effect, F1, 42 = 11.41, ## p < 0.01, interaction, F2, 42 = 2.926, p > 0.05, Fisher’s LSD post-hoc comparisons, Day 10, **p < 0.01, Day 11, *p < 0.05; Group 1 vs. Group 2: RM two-way ANOVA, main effect, F1, 36 = 32.49, #### p < 0.0001, interaction, F2, 36 = 3.513, p < 0.05, Bonferroni’s post-hoc comparisons, Day 10, **** p < 0.0001, Day 11, ** p < 0.01). L In Group 3, dual stimulation resulted in a significant enhancement of WM performance compared to single stimulation (red column). Group 3 demonstrated notable improvement over Group 2, with no significant differences compared to Group 1 (One-way ANOVA for the comparisons of the three groups; Paired-samples t test for Group 3’s comparisons between single stimulation and dual stimulation; Group 1, n = 7, Group 2, n = 7, Group 3, n = 9). M Without manipulations, no significant differences in performance were observed among the three groups (One-way ANOVA, ns, p > 0.05). N Photoinhibition of dopaminergic terminals in DMS alone had no significant impact on WM performance (Independent Samples t test, p > 0.05). The data underlying panels E, F, L, M, and N can be found in S1 Data. Data are presented as mean ± SEM.