Fig. 9: Social reward-seeking behavior and neural representations of social reward change in a sex-dependent manner following social isolation.

a Experimental timeline showing social isolation and imaging schedule. b Male mice showed a relative increase in the number of successful social trials compared to sucrose trials completed after social isolation. Two-factor ANOVA with isolation (pre/post) and trial type (sucrose/social) as factors (interaction: p = 0.020, isolation: p = 0.97, trial type: p = 0.52) with post-hoc unpaired t tests comparing isolation within trial types (sucrose: p = 0.21, social: p = 0.0079). Male mice did not show any significant difference in choice latency (c), reward latency (d) and reward fails (e) of either trial type before and after social isolation. Two-factor ANOVA with isolation (pre/post) and trial type (sucrose/social) as factors (c, interaction: p = 0.69, isolation: p = 0.56, trial type: p = 0.40; d, interaction: p = 0.81, isolation: p = 0.21, trial type: p = 1.08*10⁻⁶; e, interaction: p = 0.91, isolation: p = 0.81, trial type: p = 0.0075) with post-hoc unpaired t tests comparing isolation within trial types (d, sucrose: p = 0.36, social: p = 0.34; e, sucrose: p = 0.95, social: p = 0.39). N = 4 male mice. f Male mice did not show a difference in the proportion of mPFC neurons significantly modulated by social reward before social isolation. Proportion z test (p = 0.91). g Average normalized fluorescence traces of mPFC neurons significantly excited by social reward before (red) and after (gray) social isolation in male mice time-locked to social reward shown (left panel). h Comparison of peak fluorescence before (n = 76 neurons) and after (n = 89 neurons) social isolation shows that neural responses to social reward decreased with social isolation in male mice (right panel). Unpaired t test (p = 4.24*10⁻⁴). i Female mice showed a relative decrease in the number of successful social trials compared to sucrose trials completed after social isolation. Two-factor ANOVA with isolation and trial type as factors (interaction: p = 0.0035, isolation: p = 0.29, trial type: p = 0.30) with post-hoc unpaired t tests comparing isolation within trial types (sucrose: p = 0.017, social: p = 0.10). Female mice did not show a difference in choice latency (j), reward latency (k) and reward fails (l) of either trial type before and after social isolation. Two-factor ANOVA with isolation and trial type as factors (j, interaction: p = 0.61, isolation: p = 0.29, trial type: p = 0.41; k, interaction: p = 0.24, isolation: p = 0.13, trial type: p = 1.00*10⁻⁴; l, interaction: p = 0.36, isolation: p = 0.29, trial type: p = 0.0005) with post-hoc unpaired t tests comparing isolation within trial types (k, sucrose: p = 0.069, social: p = 0.81; l, sucrose: p = 0.42, social: p = 0.33). N = 6 female mice. m Female mice did not show a difference in proportion of mPFC neurons significantly modulated by social reward before and after social isolation. Proportion z test (p = 0.86). n Average normalized fluorescence traces of mPFC neurons significantly excited by social reward before (red) and after (gray) social isolation in female mice time-locked to social reward (left panel). o Comparison of peak fluorescence before (n = 177 neurons) and after (n = 193 neurons) social isolation shows that neural responses to social reward increased with social isolation in female mice (right panel). Unpaired t test (p = 7.58*10⁻¹¹). *p < 0.05. Shaded error regions indicate ± SEM. Dashed line at zero indicates reward onset. Error bars indicate ± SEM. Box plots: center line denotes median, box edges indicate the 25th and 75th percentiles and whiskers extend to ±2.7σ.