2.4. Y‐maze test

Animals were tested for spatial recognition memory in a Y‐maze as previously described. 15 Briefly, the three identical arms of a Y‐maze were randomly designated as follows: the start arm (always open), in which the mouse started to explore; the novel arm, which was blocked during the 1st trial but opens during the 2nd trial; and the other arm (always open). The test consisted of two trials separated by an intertrial interval (2 hours). In the first training (acquisition) trial, mice were placed in the maze facing the end of a pseudorandomly chosen start arm and allowed to explore the maze for 5 minutes with the novel arm closed. Mice were then returned to their home cage until the second (retrieval) trial, during which they could freely explore all three arms of the maze. The time spent in each arm and the number of entries were measured and analysed from video recordings (Ethovision, Noldus Information Technology Inc, Leesburg, VA, USA). Mice were required to enter an arm with all four paws for it to be counted as an entry. Entering the novel arm more frequently and exploring it for longer periods of time indicated intact spatial recognition memory. In our study, spatial recognition memory was tested on the 7th day after TBI.