Latent inhibition, overshadowing, and blocking of a conditioned antinociceptive response in spinalized rats.

Prior research has shown that a conditioned antinociceptive response can be established in spinalized rats by pairing stimulation to one hind leg (the conditioned stimulus, or CS) with tailshock (the unconditioned stimulus, or US). This suggests that spinal mechanisms can support classical conditioning. It is well known that in intact subjects, classical conditioning is undermined by preexposure to the CS (latent inhibition) or the concurrent presentation of either a more salient CS (overshadowing) or one that has already been associated with the US (blocking). In the present paper we show that these manipulations have a similar impact on the acquisition of a conditioned antinociceptive response in spinalized rats. These findings imply that similar principles may govern the acquisition of a conditioned response across different levels of the nervous system.