TABLE 2 |.

Troubleshooting table.

step	problem	possible reason	solution
2	One or more CPP tanks or part of tank not visible on camera	Camera is not connected to power sup-ply; cap is still on lens; camera is out of focus or not properly oriented	Check the power supply; check that cap is off; reorient tank and camera
3	One or more CPP tanks not visible on computer screen	Camera is not connected to video recorder or computer cannot detect camera	Check connections from camera to video recorder. Restart computer
11, 16, 18	Animal jumps out of the aquarium or freezes in the aquarium	Background noise; excessive handling; hypersensitivity to stress in certain animals (usually low percentage of ani-mals, < ~1% if handled appropriately)	Use white noise (either from a fan or played by a radio); use physical barriers (e.g., a large box) to contain the behavioral testing tank; discard the few animals that do freeze or jump
11	Animal shows a strong initial preference for either the white or the dotted compartment	Behavioral room setup causing biased preference; intrinsic preference of the animal (low percentage, < ~1%)	Keep the behavioral room setup identical from session to session; discard animals that show strong intrinsic preference (>70% preference)
11, 16, 18	Animal shows excessive thigmotaxis	Stress; reflective nature of the tank	Minimize extrinsic stress-inducing factors such as background noise, excessive and rough handling; use non-reflective material to construct the tank
12, 21	Objects in addition to the animal are tracked	Debris in the tank; lighting conditions and contrast setup are not optimized; dots in the pattern are tracked	Keep a dropper handy to remove debris from the tank; provide optimum lighting in the behavioral room; specify maximum and minimum pixel size to exclude dots
24, 25	No CPP obtained	Inconsistent procedures for assessing the initial and final preference; crosscontamination; excessive stress shown by the animals; the nature of the drug and concentration (e.g., the drug may affect sensory, motor or learning capabilities) Genetic background; differences in size of animals	Carry out initial and final preference testing at the same time of day in all animals; use separate tanks and nets for vehicle- and drug-treated groups; carry out additional conditioning trials; test a wide concentration range; control for potential confounding effects of the drug using additional behavioral tests to assess sensory, motor and learning capabilities; use age- and size-matched animals