Figure 1. Simultaneous tracking of individual mouse behavior in the dark.

(A) Top view of the arena showing the 10 regions of interest: (1) open field, (2) Z wall, (3) water, (4 and 5) feeders, (6) on small nest, (7) on large nest, (8) block, (9) in small nest, (10) in large nest. For further details of the arena, see Figure 1—figure supplement 1. (B) Video recording and color-based tracking of a group of mice in the dark. (C) A 15-min segment of the tracked paths of each of the four mice in a group. (D) A ‘heat map’ showing the relative amount of time the mice spent in different parts of the arena. Data shown is from one typical group on the second day of the experiment (red corresponds to highly visited points, and blue to less favorable ones). (E) Individual histograms of the time spent in the different regions of the arena (same group as in D). See legend at the bottom for the color coding of the regions. (F) Distribution of continuous time periods spent by one typical mouse at each region. Most areas show a similar behavior resembling scale free distribution.

DOI: http://dx.doi.org/10.7554/eLife.00759.003

Figure 1—figure supplement 1. The color-based tracking system.

A special arena for automated tracking of individual and group behavior was designed and constructed. The arena consisted of a 70 cm × 50 cm × 50 cm cage that included several objects: a Z-shaped wall, a water dispenser, two feeders, a small nest and a large nest, an elevated block, and two elevated ramps. Two UVA fluorescent lamps were placed 3 m above the arena floor to illuminate the surrounding area during the night with 370–380 nm wavelength light. During the day the arena was lit by one white-light fluorescent lamp (36W). To prevent reflections from objects in the room, a black curtain was drawn from the fluorescent lights down to the arena. A color sensitive camera was placed 1 m above the arena.

DOI: http://dx.doi.org/10.7554/eLife.00759.004