Model e10 20

The apparatus has been described in detail elsewhere (Cunningham, Gremel & Groblewski, 2006 ). Briefly, it consisted of 12 identical acrylic and aluminum boxes (30 × 15 × 15 cm) enclosed in separate light- and sound-attenuating enclosures (Coulbourn Instruments Model E10-20). Six sets of infrared light sources and detectors were mounted opposite each other at 5-cm intervals on the long walls of each box, 2.2 cm above the floor. General activity and position (left vs. right) were recorded every minute by computer (10-ms resolution).
The floor of each box consisted of interchangeable halves made of one of two textures. The “grid” (G) floor was composed of 2.3 mm stainless-steel rods mounted 6.4 mm apart in plexiglas rails. The “hole” (H) floor was made from perforated stainless steel (16 GA) with 6.4-mm round holes in 9.5-mm staggered centers. These floor textures were selected on the basis of previous studies showing that drug-naive saline only groups of B6 and D2 mice spend about half their time on each floor type during preference tests (Cunningham, 1995 (link); Cunningham et al., 1992 (link)). The apparatus and floors were wiped down with a damp sponge and the litter paper was changed after each animal.

Conditioning was conducted using an apparatus described in detail by Cunningham and colleagues (Cunningham, Gremel, & Groblewski, 2006 (link)). Briefly, eight conditioning boxes (30 × 15 × 15 cm) were individually enclosed in larger, well-ventilated chambers (Coulbourn Instruments, Model E10–20, dimensions: 56.1 × 46 × 39.4 cm) in which sound and light were both attenuated. The conditioning boxes were each equipped with six sets of infrared photodetectors (5 cm apart, 2.2 cm above the floor) allowing for real-time activity measurements and the detection of an animal’s position. The conditioning floors used here consisted of two interchangeable halves that were either a grid or a hole pattern. Grid floors were made up of 2.3 mm stainless steel rods, mounted to acrylic sides in 6.4 mm intervals. Hole floors were made from stainless steel sheets perforated with 6.4 mm holes in a staggered manner (9.5 mm apart). These floors have been used extensively in our laboratory, and numerous studies have shown that DBA/2J mice will develop robust place conditioning using these two floor types, while showing an equal preference for both floors initially (Cunningham et al., 2003).

Twelve identical acrylic and aluminum boxes (30 × 15 × 15 cm) were located inside individual ventilated, light- and sound-attenuated enclosures (Model E10–20; Coulbourn Instruments, Allentown, PA). Six infrared emitter/detector pairs were mounted 2.2 cm above the floor and 5 cm apart along the length of the box. The detectors were attached to a computer that recorded activity counts and time spent on each side during all experimental sessions. The boxes were placed on top of transposable floor halves that served as the tactile conditioned stimuli (CSs). The grid floors had 2.3 mm stainless steel cylindrical rods mounted 6.4 mm apart on acrylic rails. The hole floors were stainless steel (16 gauge) perforated with 6.4 mm holes on 9.5 mm staggered centers, mounted on a plastic base. These floor textures were selected on the basis of previous studies showing that drug-naive control groups show no pre-conditioning bias for either floor type (Cunningham et al. 2003a (link)). Mice had access to the entire box during all sessions (one-compartment procedure). The box and floors were wiped with a damp sponge and the litter paper was changed after each animal. For a more detailed description of the apparatus, see Cunningham et al. (2006) (link).