Contextual control of aversive and avoidance responding in a flavor learning paradigm in rats

Abstract

Contextual control over aversive responding was examined in two experiments where rats were trained on a context discrimination task; a saccharin solution was paired with lithium chloride (LiCl) in one context but paired with saline in a different context. In Experiment 1, rats drank significantly less in the danger context than in the safe context, and showed aversive orofacial responses in the danger context. Contextual control transferred to a novel solution. Ten extinction trials, where rats were exposed to the danger context, produced a strong reduction in contextual control over aversive responding and a weak reduction in avoidance of the trained flavor. In Experiment 2, additional groups were added to the group described above. One group received tap water rather than saccharin solution during discrimination training, while another group did not receive fluid in the training context. Again, contextual control transferred to a novel flavor and all groups showed aversive responding in the danger context and avoidance of the danger context on a place choice test. Post-extinction tests revealed that context avoidance was weakest in the group trained with saccharin solution, even though that group showed the slowest extinction of the contextual control over consumption. Additionally, differential gaping was slower to appear and faster to extinguish than chin rubbing in all groups, suggesting that these responses have different underlying mechanisms. Associative mechanisms underlying contextual control over aversive and avoidance responses are discussed.