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. 2018 Oct 8;7:e34032. doi: 10.7554/eLife.34032

Figure 1. dMSN self-stimulation elicits rapid and persistent NMDAR-independent reinforcement.

(a) Schematic of a sagittal brain section showing optogenetic stimulation of striatal dMSNs (left), and slice showing fluorescent dMSNs after striatal infusion of a Cre-dependent virus encoding eYFP in a D1-Cre mouse (right). (b) Schematic of the behavioral apparatus showing active (laser-paired) and inactive nosepokes. (c) Example cumulative plot of active nosepokes from a D1-ChR2 (blue) and D1-eYFP (black) mouse. (d) Average nosepokes during a single self-stimulation session for D1-ChR2 and D1-eYFP mice (n = 11 and 8, two-way ANOVA, interaction poke x group, F(1,17)=31.03, p<0.001, posthoc Sidak’s multiple comparisons test, ChR2 active vs eYFP active p<0.001, ChR2 active vs inactive p<0.001, eYFP active vs inactive p=0.921). (e) Average nosepokes during four consecutive daily sessions (n = 8, one-way ANOVA, F(1.908,13.36) = 1.237, p=0.319). (f) Distribution of (left) and average (right) inter-poke intervals for days 1 and 4 of dMSN self-stimulation (n = 8, paired t-test, p=0.0575). (g) Average nosepokes during an extinction session for D1-ChR2 and D1-eYFP mice (n = 8 and 8, two-way ANOVA, interaction poke x group, F(1,14)=47.86, p<0.0001, posthoc Sidak’s multiple comparisons test, ChR2 active vs eYFP active p<0.0001, ChR2 active vs inactive p<0.0001, eYFP active vs inactive p=0.5703). (h) Example cumulative plot of active nosepokes from D1-ChR2 mice expressing (D1-Cre, blue) or lacking (D1-Cre x NR1f/f, red) NMDA receptors in dMSNs. (i) Average nosepokes during a single self-stimulation session for D1-ChR2 mice with (‘D1’) or without (‘D1-NR1KO’) NMDA receptors in dMSNs (n = 9 and 7, two-way ANOVA, interaction poke x group, F(1,14)=0.638, p=0.438, posthoc Sidak’s multiple comparisons test, D1 active vs D1-NR1 active p=0.418). (j) Average distance travelled by D1-ChR2 mice with (‘D1’) or without (‘KO’) NMDA receptors in dMSNs (Mann Whitney U test, p=0.023).

Figure 1—source data 1. Source data for Figure 1.
elife-34032-fig1-data1.xlsx (63.6KB, xlsx)
DOI: 10.7554/eLife.34032.008

Figure 1.

Figure 1—figure supplement 1. Fiber placement and infusion sites.

Figure 1—figure supplement 1.

(a) Fiber tip placement in the striatum for D1-ChR2 (blue), D1-eYFP (white) and D1-NR1 (red) cohorts shown in Figure 1 (left), and intracellular slice recording from a dMSN expressing ChR2 from a D1-Cre x NR1f/f mouse injected with DIO-ChR2, showing absence of NMDA receptor-dependent current at +40 mV. (b) Fiber tip placement in the SNr for Arch3 (green) and eYFP (white) cohorts shown in Figure 3. (c) Fiber tip placement in VM for ChR2 (blue) and eYFP (white) cohorts shown in Figure 3. (d) Fiber tip placement in the DRN for ChR2 (blue) and eYFP (white) cohorts shown in Figure 3. (e) Fiber tip placement for axonal dMSN stimulation over the cerebral peduncle/anterior SNr (left), and coronal slices from mice infused with saline or FLEx-Caspase three in the DRN showing intact or absent 5HT expression in DRN, respectively (right), from mice used in Figure 4. (f) Fiber tip placement in the striatum (left) and infusion site (right) for D1-ChR2 mice infused saline (blue) or muscimol (red) used for self-stimulation or locomotion (grey) assays shown in Figure 5. (g) Left: Fiber tip placement for dMSN axonal stimulation over the cerebral peduncle (cp) in vGAT-cre mice infused with DIO-ChR2 in the striatum and DIO-ChR2 (blue) or DIO-eYFP (white) in the SNr, and coronal slice showing eYFP +dMSN fibers and fiber tip. Right: In the same mice, fiber tip placement for SNr terminal stimulation in VM, and coronal slice from a vGAT-Cre mouse infused with DIO-eYFP in the striatum and DIO-mCherry in the SNr, showing segregation of dMSN axons (green) en route to the SNr, and SNr terminals (red) in VM. From mice used in Figure 5.
Figure 1—figure supplement 2. Characterization of dMSN self-stimulation.

Figure 1—figure supplement 2.

(a) Relationship between laser duration and poke rate. Dotted box highlights chosen parameter for further experiments. (b) Relationship between stimulation pattern and poke rate (all stimuli delivered for 1 s). Dotted box highlights chosen parameter for further experiments. (c) Relationship between the number of nosepokes required to obtain laser (Fixed Ratio), poke rate, and laser exposure. (d) Average nosepoke rate before, during, and after a contingency degradation session (Deg), during which mice received an average of 5 × 1 s of laser per minute non-contingent on nosepokes (n = 8, one-way ANOVA, treatment F(1.405,9.832) = 10.11, p=0.007, posthoc Tukey’s multiple comparisons test, preTrain vs Deg p=0.016, Deg vs postTrain p=0.001). (f) Relationship between stimulation pattern and poke rate (all stimuli delivered for 1 s) for dMSN axon self-stimulation over the cerebral peduncle.
Figure 1—figure supplement 2—source data 1. Source data for Figure 1—figure supplement 2.
elife-34032-fig1-figsupp2-data1.xlsx (37.6KB, xlsx)
DOI: 10.7554/eLife.34032.005
Figure 1—figure supplement 3. dMSN self-stimulation pattern is stable over days.

Figure 1—figure supplement 3.

(a) Average number of poking bursts for days 1 and 4 of dMSN self-stimulation with criterion of inter poke interval (ipi) <2 s or <6 s (paired t-test,<2 s p=0.364;<6 s p=0.396). (b) Average number of nosepokes/bursts for days 1 and 4 of dMSN self-stimulation with criterion of inter poke interval (ipi) <2 s or <6 s (Wilcoxon signed rank test,<2 s p=0.383;<6 s p=0.383).
Figure 1—figure supplement 3—source data 1. Source data for Figure 1—figure supplement 3.
elife-34032-fig1-figsupp3-data1.xlsx (36.3KB, xlsx)
DOI: 10.7554/eLife.34032.007