2.2.4. Vertical pole test

The vertical pole test evaluates the ability of a mouse to grasp, manoeuvre and descend a pole and is widely used to assess basal ganglia‐associated movement disorders in rodents. A pole measuring 1 cm in diameter and 55 cm in length was erected within a home cage to encourage descent into the familiar environment. To train mice in the task, mice were placed facing downwards on the vertical pole for a single trial to encourage descent into the home cage. For formal testing, mice were handled by the operator for 30 s to become habituated to manual handling. Trials were initiated by placing the mouse at the top of the pole, facing upwards. Once it was adequately supporting its weight, a cap was placed above the mouse to ensure it did not ascend the pole. The mouse would then turn and descend the pole, with each trial filmed with a digital camera (Canon EOS M3 Mirrorless DSLR, Tokyo, Japan). A total of five trials were completed for each mouse, with approximately 3 min between each trial. Between each cage, the investigator's gloves and the vertical pole were cleaned with 70% ethanol to prevent olfactory cues which may alter behaviour.

Videos were played in VideoLAN Client (VLC) media player with VLC extension Time v3.2, which provides an accurate running time on the screen of a playing video. Two measures of mouse performance were quantified: the time to turn 180° with both paws facing downwards (‘time to turn’) and the total time to descend the entire 50‐cm testing region of the pole (‘time to descend’). The fastest time over the five trials was recorded for each mouse. Mice were tested at baseline (i.e., before MPTP/saline injected) and at 9 days post‐injection. The performance of each mouse at Day 9 post‐injection was normalized to their corresponding baseline performance.