Freezing (immobility) in the presence of aversive stimuli is a species-specific behavior that is used as an operational measure of fear. Conditioning of this response to discrete sensory stimuli and environmental context cues has been used as a tool to study the neuropsychology of memory dynamics and their development over the lifespan. Three age groups of F344 rats (3, 9, and 27 month) receive...

This study examined physiological indicants of the neurobiological mediators of negative affect during acute nicotine withdrawal. Eighty subjects (41 male) were assigned to one of four groups (24-h deprived or nondeprived dependent smokers, occasional smokers, and nonsmokers) and participated in an instructed fear conditioning paradigm involving cued administration of electric shock. Negative a...

Previous studies have shown that individuals with anxiety disorders exhibit deficits in fear inhibition and excessive generalization of fear, but little data exist on individuals at risk from these disorders. The present study examined the role of trait anxiety in the acquisition and generalization of fear in 126 healthy participants selected on the basis of their trait-anxiety scores. Measures...

The retrieval-extinction paradigm, which disrupts the reconsolidation of fear memories in humans, is a non-invasive technique that can be used to prevent the return of fear in humans. In the present study, unconditioned stimulus revaluation was applied in the retrieval-extinction paradigm to investigate its promotion of conditioned fear extinction in the memory reconsolidation window after part...

Domesticated animals tend to develop a coherent set of phenotypic traits. Tameness could be a central underlying factor driving this, and we therefore selected red junglefowl, ancestors of all domestic chickens, for high or low fear of humans during six generations. We measured basal metabolic rate (BMR), feed efficiency, boldness in a novel object (NO) test, corticosterone reactivity and basal...

It is widely accepted that the amygdala plays a critical role in acquisition and consolidation of fear-related memories. Some of the more widely employed behavioral paradigms that have assisted in solidifying the amygdala's role in fear-related memories are associative learning paradigms. With most associative learning tasks, a neutral conditioned stimulus (CS) is paired with a salient uncondit...

bstract—Fear conditioning and fear extinction play key oles in the development and treatment of anxiety-related isorders, yet there is little information concerning experienial variables that modulate these processes. Here we examned the impact of exposure to a stressor in a different envionment on subsequent fear conditioning and extinction, and hether the degree of behavioral control that the...

Theta oscillations are considered crucial mechanisms in neuronal communication across brain areas, required for consolidation and retrieval of fear memories. One form of inhibitory learning allowing adaptive control of fear memory is extinction, a deficit of which leads to maladaptive fear expression potentially leading to anxiety disorders. Behavioral responses after extinction training are th...

This review considers recent research assessing psychophysiological reactivity to fear imagery in anxiety disorder patients. As in animal subjects, fear cues prompt in humans a state of defensive motivation in which autonomic and somatic survival reflexes are markedly enhanced. Thus, a startle stimulus presented in a fear context yields a stronger (potentiated) reflex, providing a quantitative ...

31 Pathological anxiety is thought to reflect a maladaptive state characterized by exaggerated 32 fear. Naturally occurring perturbations that reduce fear can be crucial in the search for new 33 treatments. The protozoan parasite Toxoplasma gondii invades rat brain and removes fear of 34 rats for cat odors, a change believed to be parasitic manipulation of host behavior aimed at 35 increasing p...