*4.9. Statistical Analysis*

All data analyses were conducted using a blind test to reduce researcher bias. All quantified results in the present study were displayed as the mean value ± standard error of mean (SEM), and statistically significant differences were considered at *p* < 0.05. Behavioral data were analyzed by analysis of variance (ANOVA) using Statistical Package for the Social Sciences (SPSS, Chicago, IL, USA). Comparisons between vehicle and NAC-treated groups were conducted with the Mann–Whitney U test, and other comparisons between 4 groups and the remaining data were analyzed by the Kruskal–Wallis test with post-hoc Bonferroni correction. Non-parametric tests were chosen because of the small sample size and lack of normally distributed data.

**Author Contributions:** D.K.H. researched the data, and wrote and edited the manuscript; A.R.K., S.H.L., J.H.J., B.S.K., D.H.K. and M.K.P. researched the data; K.-H.P., M.-S.L. reviewed and edited the manuscript. B.Y.C. and S.W.S. contributed to conceptualization and supervision of the study, and editing and writing of the manuscript. All authors read and approved the final manuscript.

**Funding:** This study was supported by funding from the National Research Foundation of Korea (NRF) (NRF-2019R1A6A3A13093671) to D.K.H. and (NRF-2019R1A2C4004912) to B.Y.C. This work was also supported by the Brain Research Program through the NRF, funded by the Ministry of Science, Information and Communication Technology and Future Planning (NRF-2017M3C7A1028937, 2018R1A4A1020922 and 2020R1A2C2008480) to S.W.S.

**Conflicts of Interest:** The authors declare no conflict of interest.
