Impairments in conditioned stimulus processing and conditioned responding after combined selective removal of hippocampal and neocortical cholinergic input.

In animals, the reappearance of conditioned fear responses after extinction has been primarily investigated using single-cue conditioning paradigms. However, a differential paradigm can overcome several of the disadvantages associated with a single-cue procedure. In the present study, the reinstatement phenomenon was assessed in mice using a differential conditioned suppression paradigm. In a first phase, one conditioned stimulus (CS +) was consistently paired with an unconditioned stimulus (US; footshock) while another CS (CS–) was not, resulting in selective suppression of previously trained instrumental behaviour during the CS +. After the extinction phase, half of the animals (reinstatement group) were presented with unsignalled USs, while the other half were not (control group). A differential return of conditioned responding was observed in the reinstatement group, but not in the control group. The implications of these findings for future conditioning research are discussed.

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Increased concentration of cerebral kynurenic acid alters stimulus processing and conditioned responding

Behavioural Brain Research ◽

10.1016/j.bbr.2006.03.006 ◽

2006 ◽

Vol 170 (2) ◽

pp. 326-332 ◽

Cited By ~ 53

Author(s):

Amy C. Chess ◽

David J. Bucci

Keyword(s):

Kynurenic Acid ◽

Stimulus Processing ◽

Conditioned Responding

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Prevention of the degraded-contingency effect by signalling training trials

The Quarterly Journal of Experimental Psychology Section B ◽

10.1080/713932719 ◽

2000 ◽

Vol 53 (2b) ◽

pp. 97-119 ◽

Cited By ~ 4

Author(s):

Lisa M. Gunther ◽

Ralph R. Miller

Keyword(s):

Conditioned Stimulus ◽

Underlying Mechanism ◽

Excitatory Conditioning ◽

Retrospective Revaluation ◽

Target Conditioned Stimulus ◽

Stimulus Effect ◽

Conditioned Responding ◽

Effect Experiment ◽

Contingency Effect

Presentation of unsignalled unconditioned stimuli (USs) interspersed among Pavlovian excitatory conditioning trials weakens conditioned responding to a target conditioned stimulus (CS; Rescorla, 1968). However, signalling these intertrial USs with another cue (a cover stimulus) has been shown to alleviate this degraded-contingency effect (e.g. Durlach, 1982, 1983). In contrast to signalling the inter-trial USs, the present experiments examined the effect on the degraded-contingency effect of signalling the target CS-US pairings. Experiment 1, using parameters selected to avoid overshadowing, found that consistently presenting a cover stimulus immediately prior to the target CS-US pairings during degraded-contingency training alleviated the degraded-contingency effect. Experiment 2 examined the underlying mechanism responsible for this cover-stimulus effect through posttraining associative inflation of the cover stimulus or the context, and found that inflation of the cover stimulus attenuated responding to the target CS (i.e. empirical retrospective revaluation). The results are discussed in terms of various acquisition- and expression-focused models of acquired responding.

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