The neuronal systems that promote protective defensive behaviours have been studied extensively using Pavlovian conditioning. In this paradigm, an initially neutral-conditioned stimulus is paired with an aversive unconditioned stimulus leading the subjects to display behavioural signs of fear. Decades of research into the neural bases of this…

The 5-HT [subscript 3] receptor, the only ionotropic 5-HT receptor, is expressed in limbic regions, including the hippocampus, amygdala, and cortex. However, it is not known whether it has a role in fear memory processes. Analysis of 5-HT [subscript 3A] receptor knockout mice in fear conditioning paradigms revealed that the 5-HT [subscript 3A]…

The immediate-early gene early growth response gene-1 (EGR-1, zif-268) has been extensively studied in synaptic plasticity and memory formation in a variety of memory systems. However, a convincing role for EGR-1 in amygdala-dependent memory consolidation processes has yet to emerge. In the present study, we have examined the role of EGR-1 in the…

Plasticity in two input pathways into the lateral nucleus of the amygdala (LA), the medial prefrontal cortex (mPFC) and the sensory thalamus, have been suggested to underlie extinction, suppression of a previously acquired conditioned response (CR) following repeated presentations of the conditioned stimulus (CS). However, little is known about…

We examined whether repeated reactivations of a context memory would prevent the typical amnesic effects of post-training damage to the hippocampus (HPC). Rats were given a single contextual fear-conditioning session followed by 10 reactivations, involving a brief return to the conditioning context (no shock). Subsequently, the rats received sham…

Contextual stimulus control over instrumental drug-seeking behavior relies on the reconsolidation of context-response-drug associative memories into long-term memory storage following retrieval-induced destabilization. According to previous studies, the basolateral amygdala (BLA) and dorsal hippocampus (DH) regulate cocaine-related memory…

Excessively devaluing delayed reinforcers co-occurs with a wide variety of clinical conditions such as drug dependence, obesity, and excessive gambling. If excessive delay discounting is a trans-disease process that underlies the choice behavior leading to these and other negative health conditions, efforts to change an individual's discount rate…

Two-way active avoidance (2WAA) involves learning Pavlovian (association of a sound cue with a foot shock) and instrumental (shock avoidance) contingencies. To identify regions where dopamine (DA) is involved in mediating 2WAA, we restored DA signaling in specific brain areas of dopamine-deficient (DD) mice by local reactivation of conditionally…

We examined the roles of the amygdala and hippocampus in the formation of emotionally relevant memories using an ethological model of conditioned fear termed conditioned defeat (CD). Temporary inactivation of the ventral, but not dorsal hippocampus (VH, DH, respectively) using muscimol disrupted the acquisition of CD, whereas pretraining VH…

Using a two-way signaled active avoidance (2-AA) learning procedure, where rats were trained in a shuttle box to avoid a footshock signaled by an auditory stimulus, we tested the contributions of the lateral (LA), basal (B), and central (CE) nuclei of the amygdala to the expression of instrumental active avoidance conditioned responses (CRs).…

The terrestrial slug "Limax" exhibits a highly developed ability to learn odors with a small nervous system. When a fluorescent dye, Lucifer Yellow (LY), is injected into the slug's body cavity after odor-taste associative conditioning, a group of neurons in the procerebral (PC) lobe, an olfactory center of the slug, is labeled by LY. We examined…

Synaptically released Zn[superscript 2+] is a potential modulator of neurotransmission and synaptic plasticity in fear-conditioning pathways. Zinc transporter 3 (ZnT3) knock-out (KO) mice are well suited to test the role of zinc in learned fear, because ZnT3 is colocalized with synaptic zinc, responsible for its transport to synaptic vesicles,…

Group 1 metabotropic glutamate receptors are known to play an important role in both synaptic plasticity and memory. We show that activating these receptors prior to fear conditioning by infusing the group 1 mGluR agonist, (R.S.)-3,5-dihydroxyphenylglycine (DHPG), into the basolateral region of the amygdala (BLA) of adult Sprague-Dawley rats…

There is no clear identification of the neurons involved in fear conditioning in the amygdala. To search for these neurons, we have used a genetic approach, the "fos-tau-lacZ" (FTL) mouse, to map functionally activated expression in neurons following contextual fear conditioning. We have identified a discrete population of neurons in the lateral…

The Src protein tyrosine kinase plays a central role in the regulation of N-methyl-d-aspartate receptor (NMDAR) activity by regulating NMDAR subunit 2B (NR2B) surface expression. In the amygdala, NMDA-dependent synaptic plasticity resulting from convergent somatosensory and auditory inputs contributes to emotional memory; however, the role of Src…