Prefrontal dopamine loss delays extinction of cued fear conditioning responses, but its role in contextual fear conditioning has not been explored. Medial prefrontal lesions also enhance social interaction in rats, but the role of prefrontal dopamine loss on social interaction memory is not known. Besides, a role for subcortical accumbal dopamine on mnesic changes after prefrontal dopamine mani...

Glutamate and gamma-aminobutyric acid (GABA) release in the amygdala are thought to be crucial for the acquisition and expression of fear memories, but the time course of amino acid changes during conditioning is unknown. We used rapid-sampling microdialysis with 14 s temporal resolution to address this issue. During auditory fear conditioning, large, rapid and transient increases in glutamate ...

It has long been recognized that humans vary in their conditionability, yet the factors that contribute to individual variation in emotional learning remain to be delineated. The goal of the present study was to investigate the relationship among sex, stress hormones, and fear conditioning in humans. Forty-five healthy adults (22 females) underwent differential delay conditioning, using fear-re...

In Pavlovian fear conditioning, a conditional stimulus (CS, usually a tone) is paired with an aversive unconditional stimulus (US, usually a foot shock) in a novel context. After even a single pairing, the animal comes to exhibit a long-lasting fear to the CS and the conditioning context, which can be measured as freezing, an adaptive defense reaction in mice. Both context and tone conditioning...

The present study examined the involvement of the 5-HT(1A) receptors in classical fear conditioning using the 5-HT(1A) agonist 8-hydroxy-2-(di-n-propyloamino)tetralin hydrobromide (8-OH-DPAT) and the selective "silent" 5-HT(1A) receptor antagonist (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclo- hexane carboxamide trihydrochloride (WAY 100635). The drugs were administered b...

learning that involves the association of stimuli and their aversive consequences. In this paradigm, the animal receives pairings of an innocuous conditioned stimulus (CS), such as a tone or the context of the conditioning chamber, and a noxious unconditioned stimulus (US), such as a footshock. After a few such pairings, the CS comes to elicit a constellation of conditioned responses (CRs) that...

Chronic stress induces dendritic atrophy in the inferior colliculus (IC, auditory mesencephalon) and impairs auditory avoidance conditioning. The aim of this study was to determine in Golgi preparations and in cued fear conditioning whether stress affects other auditory components, like the thalamic medial geniculate nucleus (MG) or the posterior thalamic nucleus (PO), in Sprague-Dawley rats. C...

Nitric oxide (NO) has been widely implicated in synaptic plasticity and memory formation. In studies of long-term potentiation (LTP), NO is thought to serve as a 'retrograde messenger' that contributes to presynaptic aspects of LTP expression. In this study, we examined the role of NO signaling in Pavlovian fear conditioning. We first show that neuronal nitric oxide synthase is localized in the...

Long-term synaptic modifications in afferent inputs to the amygdala underlie fear conditioning in animals. Fear conditioning to a single sensory modality does not generalize to other cues, implying that synaptic modifications in fear conditioning pathways are input specific. The mechanisms of pathway specificity of long-term potentiation (LTP) are poorly understood. Here we show that inhibition...

................................................................................................ 2 Introduction............................................................................................4 Classical Conditioning........................................................................ 4 Fear Conditioning.................................................................................