The efficacy of pharmacological disruption of fear memory reconsolidation depends on several factors, including memory strength and age. We built on previous observations that systemic treatment with the nootropic nefiracetam potentiates cued fear memory destabilization to facilitate mifepristone-induced reconsolidation impairment. Here, we…

In cocaine use disorder, relapse can be elicited by drug-associated cues despite long periods of abstinence. The persistence of drug-associated cues in eliciting drug seeking suggests enduring changes in structural and functional plasticity, which may be mediated by basic fibroblast growth factor (bFGF, FGF2). Stimulant drug use increases bFGF…

Numerous investigations have definitively shown amygdalar involvement in delay and contextual fear conditioning. However, much less is known about amygdala contributions to trace fear conditioning, and what little evidence exists is conflicting as noted in previous studies. This discrepancy may result from selective targeting of individual nuclei…

These experiments examined the relationship between the neurotrophic factor fibroblast growth factor 2 (FGF2) and individual differences in the expression of conditioned fear. Experiments 1 and 2 demonstrated that rats naturally expressing low levels of contextual or cued fear have higher levels of hippocampal FGF2 relative to rats that express…

It has been suggested that, unlike pure extinction which typically results in the return of the fear response under a variety of circumstances, memory reactivation followed by extinction can attenuate the reemergence of conditioned fear. The reactivation-extinction procedure has attracted the attention of basic and clinical researchers due to its…

We investigated the specific role of zinc present in large amounts in the synaptic vesicles of mossy fibers and coreleased with glutamate in the CA3 region. In previous studies, we have shown that blockade of zinc after release has no effect on the consolidation of spatial learning, while zinc is required for the consolidation of contextual fear…

Some memories enter into a labile state after retrieval, requiring reconsolidation in order to persist. One functional role of memory reconsolidation is the updating of existing memories. There are reports suggesting that reconsolidation can be modulated by a particular endogenous process taking place concomitantly to its natural course, such as…

The ubiquitin-proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this…

A distributed limbic-corticostriatal circuitry is implicated in cue-induced drug craving and relapse. Exposure to drug-paired cues not only precipitates relapse, but also triggers the reactivation and reconsolidation of the cue-drug memory. However, the limbic cortical-striatal circuitry underlying drug memory reconsolidation is unclear. The aim…

Exposure to novel contexts produce heightened states of arousal and biochemical changes in the brain to consolidate memory. However, processes permitting simple exposure to unfamiliar contexts to elevate sympathetic output and to improve memory are poorly understood. This shortcoming was addressed by examining how novelty-induced changes in…

An issue of increasing theoretical interest in the study of learning is to compare the processes that follow an initial learning experience (such as learning an association between a context and a shock; memory consolidation processes) with those that follow retrieval of that learning experience (such as exposure to the context in the absence of…

Rats were subjected to one or two cycles of fear conditioning and extinction, injected with a benzodiazepine, midazolam, before the first or second extinction, and tested for long-term inhibition of fear responses (freezing). In Experiment 1, inhibition of context-conditioned fear was spared when midazolam was injected before the second…

Dihydropyridine (DHP) L-type Ca[superscript 2+] channel (LTCC) antagonists, such as nifedipine, have been reported to impair the extinction of conditioned fear without interfering with its acquisition. Identification of the LTCC isoforms mediating this DHP effect is an essential basis to reveal their role as potential drug targets for the…

Within the amygdala, most N-methyl-D-aspartic acid (NMDA) receptors consist of NR1 subunits in combination with either NR2A or NR2B subunits. Because the particular subunit composition greatly influences the receptors' properties, we investigated the contribution of both subtypes to fear conditioning and expression. To do so, we infused the…

Contexts and discrete cues associated with drug-taking are often responsible for relapse among addicts. Animal models have shown that interference with the reconsolidation of drug-cue memories can reduce seeking of drugs or drug-paired stimuli. One such model is conditioned place preference (CPP) in which an animal is trained to associate a…