Contextual Fear Extinction and Re-Extinction in Carioca High- and Low-Conditioned Freezing Rats

Gomes, Vítor de Castro; León, Laura; Mograbi, Daniel C.; Cárdenas, Fernando P.; Landeira-Fernández, J.

doi:10.4236/wjns.2014.43028

Cited by 6 publications

(2 citation statements)

References 25 publications

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“…As conditioning and extinction repeat, the residual activity of the fear neural unit accumulates and becomes saturated. In fact, it has been seen in the literature that the re-conditioned fear memory exhibited substantial resistance to re-extinction [ 51 – 54 ]. Hence, the basic model based on crosstalk between the fear, persistent and extinction neurons processed the probabilistic nature of the pairing, i .…”

Section: Resultsmentioning

confidence: 99%

Uncertainty-Dependent Extinction of Fear Memory in an Amygdala-mPFC Neural Circuit Model

et al. 2016

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Uncertainty of fear conditioning is crucial for the acquisition and extinction of fear memory. Fear memory acquired through partial pairings of a conditioned stimulus (CS) and an unconditioned stimulus (US) is more resistant to extinction than that acquired through full pairings; this effect is known as the partial reinforcement extinction effect (PREE). Although the PREE has been explained by psychological theories, the neural mechanisms underlying the PREE remain largely unclear. Here, we developed a neural circuit model based on three distinct types of neurons (fear, persistent and extinction neurons) in the amygdala and medial prefrontal cortex (mPFC). In the model, the fear, persistent and extinction neurons encode predictions of net severity, of unconditioned stimulus (US) intensity, and of net safety, respectively. Our simulation successfully reproduces the PREE. We revealed that unpredictability of the US during extinction was represented by the combined responses of the three types of neurons, which are critical for the PREE. In addition, we extended the model to include amygdala subregions and the mPFC to address a recent finding that the ventral mPFC (vmPFC) is required for consolidating extinction memory but not for memory retrieval. Furthermore, model simulations led us to propose a novel procedure to enhance extinction learning through re-conditioning with a stronger US; strengthened fear memory up-regulates the extinction neuron, which, in turn, further inhibits the fear neuron during re-extinction. Thus, our models increased the understanding of the functional roles of the amygdala and vmPFC in the processing of uncertainty in fear conditioning and extinction.

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Section: Resultsmentioning

confidence: 99%

Uncertainty-Dependent Extinction of Fear Memory in an Amygdala-mPFC Neural Circuit Model

et al. 2016

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“…The results of our ongoing breeding program have shown a clear divergence of the conditioned freezing phenotype after only three generations (Castro-Gomes and Landeira-Fernandez, 2008). The presence of different levels of anxiety-like behavior, that are characteristic of each line, can be assessed using several behavioral tests, including the elevated plus maze (EPM), the social interaction test and defensive responses that are induced by electrical stimulation of the dorsal periaqueductal gray (Dias et al, 2009; Galvão et al, 2010; Castro-Gomes et al, 2011, 2014; Salviano et al, 2014). These two lines represent an important tool for investigating the anxiogenic/anxiolytic pharmacological profiles of various compounds (Castro-Gomes et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Behavioral Effects of Systemic, Infralimbic and Prelimbic Injections of a Serotonin 5-HT2A Antagonist in Carioca High- and Low-Conditioned Freezing Rats

León

Castro-Gomes

Zárate-Guerrero

et al. 2017

Front. Behav. Neurosci.

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The role of serotonin (5-hydroxytryptamine [5-HT]) and 5-HT2A receptors in anxiety has been extensively studied, mostly without considering individual differences in trait anxiety. Our laboratory developed two lines of animals that are bred for high and low freezing responses to contextual cues that are previously associated with footshock (Carioca High-conditioned Freezing [CHF] and Carioca Low-conditioned Freezing [CLF]). The present study investigated whether ketanserin, a preferential 5-HT2A receptor blocker, exerts distinct anxiety-like profiles in these two lines of animals. In the first experiment, the animals received a systemic injection of ketanserin and were exposed to the elevated plus maze (EPM). In the second experiment, these two lines of animals received microinjections of ketanserin in the infralimbic (IL) and prelimbic (PL) cortices and were exposed to either the EPM or a contextual fear conditioning paradigm. The two rat lines exhibited bidirectional effects on anxiety-like behavior in the EPM and opposite responses to ketanserin. Both systemic and intra-IL cortex injections of ketanserin exerted anxiolytic-like effects in CHF rats but anxiogenic-like effects in CLF rats. Microinjections of ketanserin in the PL cortex also exerted anxiolytic-like effects in CHF rats but had no effect in CLF rats. These results suggest that the behavioral effects of 5-HT2A receptor antagonism might depend on genetic variability associated with baseline reactions to threatening situations and 5-HT2A receptor expression in the IL and PL cortices.Highlights CHF and CLF rats are two bidirectional lines that are based on contextual fear conditioning.CHF rats have a more “anxious” phenotype than CLF rats in the EPM.The 5-HT2A receptor antagonist ketanserin had opposite behavioral effects in CHF and CLF rats.Systemic and IL injections either decreased (CHF) or increased (CLF) anxiety-like behavior.PL injections either decreased (CHF) anxiety-like behavior or had no effect (CLF).

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On Becoming a Brazilian Full Professor in Psychology

Landeira-Fernández

2019

Psychology in Brazil

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Contextual Fear Extinction and Re-Extinction in Carioca High- and Low-Conditioned Freezing Rats

Cited by 6 publications

References 25 publications

Uncertainty-Dependent Extinction of Fear Memory in an Amygdala-mPFC Neural Circuit Model

Uncertainty-Dependent Extinction of Fear Memory in an Amygdala-mPFC Neural Circuit Model

Behavioral Effects of Systemic, Infralimbic and Prelimbic Injections of a Serotonin 5-HT2A Antagonist in Carioca High- and Low-Conditioned Freezing Rats

On Becoming a Brazilian Full Professor in Psychology

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