Ethovision xt 14 video tracking system

The OFT has been widely used to evaluate the locomotor activity and anxiety-like behaviors in an open-field arena^{104 (link)}. All experimental mice were transferred to the behavioral testing room at least 1 hr before the tests to reduce stress and to acclimatize to the environment. The test chamber (40 × 40 × 35 cm) was made of gray plastic, which was divided into a central field (center, 20 × 20 cm) and an outer field (periphery). Mice were individually placed in the center area of the chamber, and their paths were recorded by a video camera. To examine the effect of photostimulation of NG2 glia, the animals were tested during 25-min sessions (consisting of 5 min light off-on-off-on-off periods). Blue light (470 nm, 8–10 mW, 10 sec ON/OFF) was generated by an external laser power source (Newdoon Inc., Hangzhou, China) and delivered bilaterally during the light-on phase. Distance traveled and time spent in the center zone were analyzed with EthoVision XT 14 video tracking system (Noldus Information Technology, Wageningen, Netherlands). After each trial, the chamber was cleaned with 75% alcohol solution.

In brief, social avoidance behavior was measured according to a two-stage social interaction test. In the first stage, mice were placed in the open field arena containing a wire cup (8 cm diameter, 20 cm height) at one end of the arena. Time spent in the area surrounding the cup (interaction zone, an 8 cm region surrounding the cup) and in the corner area along the wall opposite the cup (corner zone, two 8 ×  8 cm² corner regions along the wall opposite the cup) were measured individually. The time spent in the interaction zone in the first stage was termed “No target”. Animals were then returned to the home cage for 1 min. In the second stage, an unfamiliar, aggressive CD1 mouse was confined within the cup and the same metrics were measured (termed “Target”). From these two stages, the social interaction ratio was calculated (time spent in interaction zone in “Target”/time spent in interaction zone in “No target”). In all behavioral experiments except for non-CSDS control mice, blue light was delivered as described in OFT method section and the mice’ tracks were monitored with EthoVision XT 14 video tracking system (Noldus Information Technology, Wageningen, Netherlands). The arena and wire cup were cleaned with 75% alcohol between tests.