Materials and Reagents

1. Rats
   
2. Ethanol
   
3. Targets
   1. Semi-transparent purple vinyl index card dividers (Oxford Esselte, catalog number: 73153 )
      
   2. Rodent food dishes
      
   3. Sterilized bottle caps
   Targets are pieces of plastic cut into 2” diameter circles. We use semi-transparent purple vinyl index card dividers by Oxford Esselte, but in the past have successfully used both rodent food dishes and sterilized bottle caps. The flat vinyl targets are appealing because they are simple to clean, and are less attractive to the rats to explore and carry, compared to dishes or caps. Whichever targets are employed, the targets used in a single experiment should be identical to each other.
   
4. Bait
   1. Froot Loops^® cereal (or a generic equivalent)
      
   2. Fruity Pebbles^® or Cocoa pebbles^® (one pebble per target)
   For bait, we use Froot Loops^® cereal (or a generic equivalent) broken into quarter pieces (one quarter per target), or Fruity Pebbles^® or Cocoa pebbles^® (one pebble per target). All work equally well.
   
5. Configuration Templates
   During pre-training, targets are placed randomly and do not require templates (see Procedure). In the test trials, however, the spatial arrangement of targets is critical. For this purpose, we create a template out of posterboard which is cut to fill the entire arena floor. Holes (approx. 2.5” diameter) are cut in the posterboard where the targets will be placed. Before each trial, the template is placed in the open field, and targets are then placed in the holes. The template can then be lifted out of the open field, leaving the targets located precisely in the arena.
   

Equipment

1. Open Field Arena (Figure 1)
   The animals are tested in a 90 x 90 x 75 cm open field arena made of plywood. It is painted white, with a black grid painted on the floor. Any large standard open field should work, although the same type should be used consistently since the arena size and shape are expected to affect task performance measures.
   
   
   Figure 1. Photo of the open field arena with ten baited targets and a rat
   
   
2. Stopwatch
   A simple stopwatch (minutes/seconds) is used to time the animals in the task.
   
3. Video Camera
   A video camera recording high-definition video files to SD card is used to record all trials. The video camera resolution must be sufficient to see (1) whether a piece of bait has been removed from the target in low lighting conditions, and (2) whether the vibrissa (whiskers) of the animal contact the target.
   
4. White Noise generator (e.g., HoMedics, model: SS-2000G/F-AMZ )
   We use a standard home-use white noise generator, HoMedics SS-200G/F-AMZ. Any standard model of white-noise generator designed for home or laboratory use would be appropriate. The white noise generator helps to mask any distractions due to extraneous sounds in or near the testing room, which reduces behavioral variability in the task.
   

Procedure