Motor performance was assessed in the rotarod test using a fixed speed protocol. On day 1, mice had two 60-sec training sessions at low speed (10–20 rpm) on the rotarod (Ugo Basile). On day 2, all mice were tested in random order, with two 60-sec trials at various increasing speeds (20, 25, 30 and 35 rpm). The time until the mouse fall down from the rotating rod was measured until the end of the trial (maximal time is 60 sec). The final score for each mouse was the average of two measurements at a speed of 35 rpm. For all motor behavior tests the investigator was blinded to the group allocation of each mouse.