Clinical and preclinical studies that have examined the neurobiology of persistent fear memory in posttraumatic stress disorder (PTSD) have focused on the medial prefrontal cortex, hippocampus, and amygdala. Sensory systems, the periaqueductal gray (PAG), and midline thalamic nuclei have been implicated in fear and extinction memory, but whether…

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…

Studies on the behavioral mechanisms underlying contextual fear conditioning (CFC) have demonstrated the importance of preshock context exposure in the formation of aversive context memories. However, there has been comparatively little investigation of the effects of context exposure immediately after the shock. Some models predict that…

This paper demonstrates that the phenomenographic methodology -- the study of variations of lived experience -- has the capacity to manage cultural and paradigmatic differences between researchers and participants in cross-cultural research. The process of cross-cultural research presented herein makes a contribution to the existing body of…

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…

It is well known that emotions participate in the regulation of social behaviors and that the emotion displayed by a conspecific influences the behavior of other animals. In its simplest form, empathy can be characterized as the capacity to be affected by and/or share the emotional state of another. However, to date, relatively little is known…

Increased emotionality is a characteristic of human adolescence, but its animal models are limited. Here we report that generalization of auditory conditioned fear between a conditional stimulus (CS+) and a novel auditory stimulus is stronger in 4-5-wk-old mice (juveniles) than in their 9-10-wk-old counterparts (adults), whereas nonassociative…

Individuals with anxiety disorders often do not respond to safety signals and hence continue to be afraid and anxious. Consequently, it is important to develop paradigms in animals that can directly study brain systems involved in learning about, and responding to, safety signals. We previously developed a discrimination procedure in rats of the…

Fear extinction is defined as a decline in conditioned fear responses (CRs) following nonreinforced exposure to a feared conditioned stimulus (CS). Behavioral evidence indicates that extinction is a form of inhibitory learning: Extinguished fear responses reappear with the passage of time (spontaneous recovery), a shift of context (renewal), and…