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. Author manuscript; available in PMC: 2023 Apr 24.
Published in final edited form as: Nat Neurosci. 2022 Oct 24;25(11):1505–1518. doi: 10.1038/s41593-022-01179-2

Figure 2. Mice are willing to take altruistic decisions under costly situations.

Figure 2

a, Experimental design of the SDM with different fixed ratio (FR) schedule. b, Left, Number of nose poke on FR1 versus FR2, FR4 and FR6 in males (n=7) and females (n=4) actors and actors tested without recipient (n=5) (between groups: two-way RM ANOVA, group (with recipient males, with recipient females, no recipient) x response (FR2, FR4, FR6), F(10, 52)=4.25, p=0.0002; within groups: two-way RM ANOVA, group (with recipient males, with recipient females, no recipient) x response (FR2, FR4, FR6), F(4, 26)=4.48, p=0.0069). Right, number of nose pokes on SDM day 5 (one-way ANOVA, F(2, 13)=0.67, p=0.5270). c, Decision preference scores with FR2, FR4 and FR6, compared to FR1, in mice tested with recipient (male, n=7 and female, n=4) and without recipient (n=5) (two-way ANOVA, group (with recipient males, with recipient females, no recipient) x response (FR2, FR4, FR6), F(4, 26)=3.55, p=0.0193). males: *p=0.0265 (FR4) and p=0.0678 (FR6) vs. no recipient, ##p=0.0010 vs females. d, Actors’ change in altruistic choices during devaluation test in the condition rewards to recipients only (n=6) and no reward (n=8, two-tailed paired t-test: t=2.28, d.f.=12, p=0.0410), and number of nose pokes during valued and devalued sessions (two-way RM ANOVA, session type (valued, devalued), F(1, 14)=43.07, p<0.0001). (e-f), Following SDM training altruistic choices did not result in concurrent reward for the actor. Percentage of selfish choices (e, two-way RM ANOVA, group (selfish, altruistic) x time (session 1-2), F(1, 11)=4.90, p=0.0488) and number of altruistic choices (f) over 120 minutes of SDM in mice grouped by selfish (n=7) or altruistic (n=6) preference (inset, percentage of altruistic choices in the first 40 minutes / total number of altruistic choices; two-tailed unpaired t-test, t=8.17, d.f.=10, p=0.0001). g, Selfish choices in the SDM (n=13), without concurrent reward (as in e-f), following satiety-induced reward devaluation compared to valued session (two-tailed paired t-test, t=5.41, d.f.=12, p=0.0002) and differences between altruistic (n=6) and selfish mice (n=7) (two-way RM ANOVA, group (selfish, altruistic) x time (session 1-2), F(1, 11)=6.37, p=0.0282). *p<0.05, **p<0.01, ***p<0.001. n.s. not significant. Values are expressed as mean ± s.e.m.