The retention of an incompletely learned avoidance response.

Kamin, Leon J.

doi:10.1037/h0044226

Cited by 285 publications

(152 citation statements)

References 7 publications

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“…Freezing time was measured with a stop watch. All behavioural tests were performed between 10:00 and 12:00 hr to avoid a Kamin effect (Kamin, 1957).…”

Section: Conditioned Freezing Measurementsmentioning

confidence: 99%

The H3 receptor protean agonist proxyfan enhances the expression of fear memory in the rat

et al. 2005

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Consolidation of fear memory requires neural changes to occur in the basolateral amygdala (BLA), including modulation of histaminergic neurotransmission. We previously demonstrated that local blockade or activation of histamine H 3 receptors in the BLA impaired or ameliorated, respectively, retention of fear memory. The histamine H 3 receptor is a G-protein-coupled receptor (GPCR) displaying high constitutive activity that regulates histamine neurons in the brain. Proxyfan is a high-affinity histamine H 3 receptor protean agonist exhibiting the full spectrum of pharmacological activities, from full agonist to full inverse agonist depending on the competition between constitutively active and quiescent H 3 receptors in a given tissue or brain region. Therefore, protean agonists are powerful tools to investigate receptor conformation and may be useful in designing specific compounds selective for the various receptor conformations. In the present study we examined the effect of post-training, systemic or intra-BLA injections of proxyfan on contextual fear memory. Rats receiving intra-BLA, bilateral injections of 1.66 ng proxyfan immediately after fear conditioning showed stronger memory for the context-footshock association, as demonstrated by longer freezing assessed at retention performed 72 hr later compared to controls. Comparable results were obtained when doses as low as 0.04 mg/kg of proxyfan were injected systemically. Hence, our results suggest that proxyfan behaves as an H 3 receptor agonist with a low level of constitutive activity of the H 3 receptor in the rat BLA.

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“…Freezing time was measured with a stop watch. All behavioural tests were performed between 10:00 and 12:00 hr to avoid a Kamin effect (Kamin, 1957).…”

Section: Conditioned Freezing Measurementsmentioning

confidence: 99%

The H3 receptor protean agonist proxyfan enhances the expression of fear memory in the rat

et al. 2005

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“…Figure 3B delivery in each group but are overlaid for simplicity. Group 24 h displayed higher levels of freezing across the entire extinction session than Groups Contiguous and Handled (Group × Time interaction: F (4,66) ¼ 2.59, P ¼ 0.045), presumably reflecting fear incubation over the 24 h after training (Bindra and Cameron 1953;Kamin 1957).…”

Section: Resultsmentioning

confidence: 99%

Potent attenuation of context fear by extinction training contiguous with acquisition

Bernier

Lacagnina

Drew³

2014

Learn. Mem.

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Studies on the behavioral mechanisms underlying contextual fear conditioning (CFC) have demonstrated the importance of preshock context exposure in the formation of aversive context memories. However, there has been comparatively little investigation of the effects of context exposure immediately after the shock. Some models predict that nonreinforced context exposure at the end of the acquisition session will strongly influence the strength of conditioning and/or recruit distinct neural mechanisms relative to extinction after acquisition. Here we investigate the effects of manipulating postshock context exposure on CFC in mice. Prolonging the period of context exposure immediately following the shock caused a significant and durable reduction in conditioned fear. This immediate postshock context exposure was more effective at attenuating conditioned fear than was an equivalent amount of context exposure a day or more after acquisition. The results suggest that nonreinforced exposure to the context influences conditioned fear through distinct mechanisms depending on whether it occurs during acquisition or after it. The superiority of immediate postshock context exposure was specific to single-shock CFC; in two-shock CFC, immediate and delayed postshock context exposure had similar effects. Consistent with previous reports, we hypothesize that the effectiveness of extinction is modulated by emotional state, and procedures engendering higher postshock freezing (such as two-shock CFC) are associated with weaker immediate extinction.Contextual fear conditioning (CFC) is a form of associative learning that occurs when an aversive experience, usually a footshock in laboratory experiments, occurs within a distinctive place or context. Learned contextual fear typically recruits plasticity in the hippocampus, which is thought to generate a conjunctive mnemonic representation of stimuli present during the learning episode (Rudy et al. 2004;Fanselow 2010). The robustness of this form of learning has made it one of the preferred methods for studying mechanisms of hippocampus-dependent memory and learned fear.While the neural mechanisms of CFC have been researched extensively, there has been comparatively little investigation of the behavioral mechanisms through which the emotional valence of a context is established. One longstanding idea is that the strength of context conditioning is determined by the overall rate of unconditioned stimulus (US) presentation per unit time in the context (Rescorla and Wagner 1972;Gibbon and Balsam 1981). This approach accounts for the observation that increasing the intertrial interval in conditioning experiments tends to decrease the amount of conditioned responding elicited by the context (Fanselow et al. 1993;Barela 1999). However, this model fails to account for a key property of CFC: very brief preshock context exposure leads to an absence of context fear, rather than robust fear as the rate-based model would predict (Fanselow 1986). This phenomenon, known as the immediate shock defici...

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“…An impressive series of papers in the 1970s by Holloway and Wansley (e.g., 1973) demonstrated the complexity of this question. Earlier on, Leon Kamin (1957) had described the temporary suppression of retrieval of a learned passive avoidance task circa 6 h after training. 24 h after training, the information turned out to be fully present, and the performance on the task was just as good as 15 min after training.…”

Section: Circadian Phase Dependence Of Learningmentioning

confidence: 99%

Learning and Circadian Behavior

Daan

2000

J Biol Rhythms

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The retention of an incompletely learned avoidance response.

Cited by 285 publications

References 7 publications

The H3 receptor protean agonist proxyfan enhances the expression of fear memory in the rat

The H3 receptor protean agonist proxyfan enhances the expression of fear memory in the rat

Potent attenuation of context fear by extinction training contiguous with acquisition

Learning and Circadian Behavior

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