Changes in Memory for Stimulus Attributes: Implications for Tests of Morphine Tolerance

Abstract

One major class of evidence indicating that associative processes contribute significantly to the development of morphine tolerance is based on the context specificity of the phenomenon: Changing the stimulus context correlated with drug administration diminishes tolerance. If this outcome is analogous to stimulus generalization decrement in traditional learning studies, then the flattening of generalization gradients over time may modulate the traditional test for tolerance. Accordingly, the effect of retention interval on context specificity of tolerance in rats was investigated. A hot-plate pain sensitivity test indicated that a context shift disrupted tolerance after a short, but not a long, retention interval. Methodological implications for assessment of learning processes in tolerance are noted.