Effects of combining tactile with visual and spatial cues in conditioned place preference

Previous research provides little information about variables that determine which elements of contextual cues gain associative control over behavior in the conditioned place preference (CPP) procedure. These studies examined the effect of external visual-spatial cues on CPP when tactile cues served as the conditioned stimuli. DBA/2J mice were trained in the dark (Experiment 1) or light (Experiment 2) using unbiased procedures in which the spatial location of an ethanol-paired tactile cue during training was relevant (two-compartment procedure) or irrelevant (one-compartment procedure). All groups developed CPP, but it was weakest after one-compartment training in the light. In Experiment 3, tactile cues were tested either in the same locations used during training or reversed after two-compartment training in either the dark or light. CPP was unaffected by cue location reversal in the dark, but it was reduced when cue locations changed in the light. Mice in Experiment 4 also received two-compartment training in either the light or dark, but the spatial locations of the drug- and vehicle-paired cues alternated over trials, making external visual-spatial cues irrelevant. In this case, lighting had no effect on CPP. These studies show that cue location does not affect CPP when tactile cue training occurs in the dark. Moreover, they suggest that external visual-spatial cues might enhance CPP when those cues are relevant, but not when an alternating two-compartment procedure is used. The cue reversal effect suggests that relevant external visual-spatial cues acquire associative strength when combined with tactile cues in a two-compartment procedure in the light. Overall, these studies improve our understanding of how external visual-spatial cues interact with tactile cues during drug-induced conditioning, which could have important implications for studies that use CPP to study the neurobiological bases of drug seeking and drug reward.