Is conditioned immunosuppression truly conditioned?

Classical conditioning: The new hegemony

Converging data from different disciplines are showing the role of classical conditioning processes in the elaboration of human and animal behavior to be larger than previously supposed. Restricted views of classically conditioned responses as merely secretory, reflexive, or emotional are giving way to a broader conception that includes problem-solving, and other rule-governed behavior thought to be the exclusive province of either operant conditiońing or cognitive psychology. These new views have been accompanied by changes in the way conditioning is conducted and evaluated. Data from a number of seemingly unrelated phenomena such as relapse to drug abuse by postaddicts, the placebo effect, and the immune response appear to involve classical conditioning processes. Classical conditioning, moreover, has been found to occur in simpler and simpler organisms and recently even demonstrated in brain slices and in utero. This target article will integrate the several research areas that have used the classical conditioning process as an explanatory model; it will challenge teleological interpretations of the classically conditioned CR and offer some basic principles for testing conditioning in diverse areas.

A behavioral augmentation of natural immunity: odor specificity supports a Pavlovian conditioning model

BALB/c mice were conditioned by pairing an odor to an injection of poly-inosinic:poly-cytidylic acid (poly I:C), a strong inducer of natural killer (NK) cell activity as the unconditioned stimulus (US). When later reexposed to the odor conditioning stimulus (CS), these mice showed a conditioned augmentation of the NK cell response to a suboptimal dose of 1 microgram poly I:C. The two stimuli used in these studies were camphor (Ca) and citronella oil (Cr) odors, two chemically-related but distinct odor stimuli. The conditioned mice demonstrated the ability to discriminate between Ca and Cr, such that the conditioned response (CR) was only elicited by the odor CS used in the formation of the conditioned association. Exposure of conditioned mice to the non-associated odor stimulus on the test day did not elicit a change in the NK cell response to the suboptimal dose of poly I:C when compared to mice in the US group that had been given the US on day 0 without pairing to either odor stimulus. This specificity of the CR for the odor CS and not the unassociated odor stimulus supports the interpretation that the elevation of NK cell activity in this paradigm is due to Pavlovian conditioning and therefore dependent on central nervous system (CNS) associative processes.