Measuring Spontaneous Alternation in Y-Maze

The Y-maze apparatus consisted of three arms 32 cm (long) and 610 cm (wide) with 26-cm walls (San Diego Instruments, San Diego, CA). Testing was always performed in the same room and at the same time to ensure environmental consistency as previously described^{12 (link),13 (link)}. Briefly, each mouse was placed in the center of the Y-maze and allowed to explore freely during a 5-min session as a measure of spontaneous alternating behavior. The sequence and total number of arms entered were video-recorded. An entry into an arm was considered valid if all four paws entered the arm. An alternation was defined as three consecutive entries into three different arms (1, 2, 3, or 2, 3, 1, etc.). Percentage of alternation was calculated using the following formula: total alternation number/total number of entries−2) × 100.