Mouse behavioral experiments
The generation and characterization of the Hdh140Q knock-in mice have been previously described (44). All the behavioral experiments were performed during the light phase and the experimenters are blind to the genotype of each mouse. Both males and females have been used. All the mice were kept in the behavioral test room in dim red light for one hour before starting the experiments. For activity tests, mice were placed in a pen holder with mashed surface (98mm height x 91mm diameter) for 5 min. The rearing number indicates the total number of events when the animal lifted up at least two limbs. For open-field tests, mice were placed in a 30 x 30 x 40 cm white Plexiglas chamber (equipment from Med-Associates) in a behavior room, and locomotion was captured by camera on top of the chamber and recorded for 15 min. The traveling trace and distance were then analyzed by the Med-Associates Activity Monitor program.