Spontaneous locomotor activity was evaluated in square Plexiglas activity chambers (43.2 × 43.2 × 20 cm) equipped with three planes of infrared detectors (Med Associates Inc, St. Albans, VT). Four mice were tested concurrently in individual chambers. The chamber was divided into the center (20 cm × 20 cm, zone 1) and periphery (the rest of the chamber, zone 2). Chambers were located within sound-attenuating boxes (66 × 55.9 × 55.9 cm) with a built-in internal fan for background noise (65 dB) and lighting for ambient illumination (40 lux). For testing, each animal was placed in the center of the testing arena and allowed to move freely for 10 minutes. The movements were monitored and recorded by an automated tracking system (Med Associates Activity Monitor, version 5.93.773).
