*4.2. Animals and Experimental Groups*

Seven-week-old male C57Bl/6 mice were purchased from Central Laboratory animals Inc. (Seoul, Korea) (*n* = 32 for cohort 1, *n* = 40 for cohort 2). The mice were housed under constant temperature and humidity with 12-h cycles of light/darkness. They had *ad libitum* access to rodent chow and water. After a week of habituation, the mice were randomly assigned into experimental groups. The mice in the TBI cohort were assigned to the following assignments: (1) control (*n* = 6): DW p.o. + no TBI; (2) AG (*n* = 6): *Angelica gigas* 1 mg/kg p.o + no TBI; (3) TBI (*n* = 8): DW p.o. + TBI; (4) TBI + AG (*n* = 12): *Angelica gigas* 1 mg/kg p.o. + TBI. The mice in the CMS cohort were assigned to the following assignments: (1) control (*n* = 10): DW p.o. + no CMS; (2) AG (*n* = 10): *Angelica gigas* 1 mg/kg p.o + no CMS; 3) CMS (*n* = 10): DW p.o. + CMS; 4) CMS + AG (*n* = 10): *Angelica gigas* 1 mg/kg p.o. + CMS. The outline of the experimental procedures is schematically represented in Figure 5. Animal studies were conducted in accordance with the Guide for the Care and Use of Laboratory Animals by the NIH. The protocols were approved by the Institutional Animal Care and Use Committee of Kyung Hee University (KHUASP(GC)-17-024).

**Figure 5.** Experimental outline of mild cognitive impairment mice models induced by TBI (Cohort 1) and CMS (Cohort 2). TBI: Traumatic brain injury, CCI: Controlled cortical impact, Y-maze: Y shaped maze test, NOT: Novel object test, MWM: Morris water maze, FC: Fear conditioning, CMS: Chronic mild stress.
