The CS− effect in simple conditioning and stimulus selection during development

Abstract

Changes in affect toward a particular stimulus can take place very rapidly through Pavlovian conditioning, if presentation of the conditioned stimulus (CS+) paired with the unconditioned stimulus <US) is accompanied by presentation ofa "CS-," another value of the same dimension as the CS + but not paired with a US. This effect has considerable generality. It has been observed in terms of both olfactory and visual CSs, in terms of appetitive as well as aversive conditioning, and for adult as well as infant rats, The CS-effect has seemed especially important for infants, which may be related to the general tendency for infants to exhibit less stimulus selection than older animals. Finally, the CS -effect has enabled the development of a simple test of shortterm retention that can quite effectively assess memory for either incidental or target events. These tests so far have indicated a clear ontogenetic decrease in rate of forgetting over short intervals, corresponding to the well-known development-related decrease in forgetting over long intervals (infantile amnesia). The tests also have shown that short-term forgetting ofintentional and target events is surprisingly similar, with some indication of more rapid forgetting for the incidental events. Alternative interpretations of the CS -effect and some preliminary tests of these interpretations are discussed, During the first three weeks of the developing rat's postnatal life, there are dramatic changes in motor coordination and sensory capacities. Structural and neurochemical changes in the brain are equally dramatic. For instance, by the age of 2 weeks postnatal the rat will have undergone immense change from the hairless, relatively helpless neonate it once was, to a capable, well-coordinated animal with all sensory systems reasonably active; yet even at this point the number of neocortical synapses in this rat will increase further, by 5-1 0 times their present number within their next week or two of growth. Throughout this period of rapid postnatal growth, the rat is, from Day lon, a quite adaptive creature, capable of substantial learning (for reviews, see Kail & Spear, 1984; Spear & Campbell, 1979). In this paper, we review some issues associated with a simple procedure that can substantially affect a general instance of rapid learning that is prevalent in the developing rat.A question we have been pursuing for some time is why these very young rats, like very young people, show infantile amnesia-exaggerated forgetting for events of their infancy over a long interval that includes a period of their growth. What makes this forgetting exaggerated is that

Effects of Ontogeny on Performance of Rats in a Novel Object-Recognition Task

“…These ontogenetic trends are consistent with those found in the literature. Similar results have been dustrated by Campbell and Campbell (1962) and many others (e.g., Schulenburg, Riccio, & Stikes, 1971) using fear conditioning procedures, researchers employing appetitive tasks (e.g., Spear, Kucharski, & Miller, 1989)) and by investigators examining habituation to various sensory stimuli (e.g., Richardson & Campbell, 199 1;Hayne, Richardson, & Campbell, 1992).…”

Assessing appetitive, aversive, and negative ethanol-mediated reinforcement through an immature rat model

“…In Pautassi et al, (2005b) a tactile stimulus (CS − ) predicted the initial phase of ethanol intoxication, while the gustatory stimulus (sucrose, CS + ) was presented during a later period of the toxic processes, characterized by peak BALs. Employment of a CS − /CS + Pavlovian strategy is known to facilitate, particularly in young rats, the acquisition of aversive memories otherwise not detected through simple excitatory conditioning procedures that only utilize a CS + (Kucharski et al, 1985 Spear et al, 1989). It should also be noted that prenatal ethanol has been found to ameliorate ethanol-mediated CTA during infancy (Arias and Chotro, 2006b).…”

The influence of the information value provided by prior-cuing treatment on the reactivation of memory in preweanling rats

“…Ontogenetic differences in stimulus selection are evident in a variety of circumstances (for reviews, see Spear & Kucharski, 1984a, 1984bSpear, Kucharski, & Miller, 1989), including a tendency for younger animals to show greater conditioning to "incidental" stimuli present at the time of conditioning. For example, Solheim, Hensler, and Spear (1980) found that a shift in the context from training to testing resulted in a disruption in the performance of active avoidance in young animals that was not evident in adults.…”