We describe evidence for an evolved module for fear elicitation and fear learning with four primary characteristics. First, it is preferentially activated by stimuli related to survival threats in evolutionary history. Thus, fear-relevant stimuli lead to superior conditioning of aversive associations compared with fear-irrelevant stimuli. Second, the module is automatically activated by fear-re...

Chronic stress effects and sex differences were examined on conditioned fear extinction. Male and female Sprague-Dawley rats were chronically stressed by restraint (6 h/d/21 d), conditioned to tone and footshock, followed by extinction after 1 h and 24 h delays. Chronic stress impaired the recall of fear extinction in males, as evidenced by high freezing to tone after the 24 h delay despite exp...

Maladaptive fear, such as fear that is persistent or easily generalized to a nonthreatening stimuli, is associated with anxiety-related disorders in humans. In the laboratory, maladaptive fear can be modeled in rodents using Pavlovian fear conditioning. Recently, an inbred mouse strain known as 129S1/SvImJ, or 129S1 has been reported as exhibiting impairments in fear extinction and enhanced fea...

The contribution of the amygdala and hippocampus to the acquisition of conditioned fear responses to a cue (a tone paired with footshock) and to context (background stimuli continuously present in the apparatus in which tone-shock pairings occurred) was examined in rats. In unoperated controls, responses to the cue conditioned faster and were more resistant to extinction than were responses to ...

The hippocampus is well-known to be critical for trace fear conditioning, but nothing is known about the importance of perirhinal cortex (PR), which has reciprocal connections with hippocampus. PR damage severely impairs delay fear conditioning to ultrasonic vocalizations (USVs) and discontinuous tones (pips), but has no effect on delay conditioning to continuous tones. Here we demonstrate that...

Pavlovian fear conditioning is an evolutionary conserved and extensively studied form of associative learning and memory. In mammals, the lateral amygdala (LA) is an essential locus for Pavlovian fear learning and memory. Despite significant progress unraveling the cellular mechanisms responsible for fear conditioning, very little is known about the anatomical organization of neurons encoding f...

BACKGROUND Associative conditioning is a ubiquitous form of learning throughout the animal kingdom and fear conditioning is one of the most widely researched models for studying its neurobiological basis. Fear conditioning is also considered a model system for understanding phobias and anxiety disorders. A fundamental issue in fear conditioning regards the existence and location of neurons in t...

Discriminative fear conditioning requires learning to dissociate between safety cues and cues that predict negative outcomes yet little is known about what processes contribute to discriminative fear learning. According to attentional models of time perception, processes that distract from timing result in temporal underestimation. If discriminative fear learning only requires learning what cue...

The present study explored fear acquisition in differential delay versus trace conditioning in regard to the potential role of the acquired contingency awareness. One of two neutral pictures (CS+) either coterminated with (delay group; n=32) or was followed by the aversive unconditioned stimulus (UCS) after CS offset (trace group; n=32), while startle blink and skin conductance responses (SCR) ...