The activity chamber was used to determine general activity levels, gross locomotor activity, and exploration habits in rodents. Assessment took place in an open‐field activity arena (Med Associates Inc., St. Albans, VT. Model ENV‐515) mounted with three planes of infrared detectors, within a specially designed sound‐attenuating chamber (Med Associates Inc., St. Albans, VT. MED‐017M‐027). The arena is 43 cm (L) × 43 cm (W) × 30 cm (H), and the sound‐attenuating chamber is 74 cm (L) × 60 cm (W) × 60 cm (H). The animal was placed in the corner of the testing arena and allowed to explore the arena for 10 min while being tracked by an automated tracking system. Parameters including distance moved, time immobile, and times spent in pre‐defined zones of the arena were recorded.