Accordingly, empirical studies investigating emotion regulation have grown exponentially over the last two decades,

reflecting mounting interest within the field (Gross, 2013). Despite the broad scientific interest in understanding how emotions are regulated, however, the notion that stress may be detrimental to emotional control has been relatively overlooked within this literature. Consequently, the effects of stress on the capacity to flexibly control emotional responses have remained largely unexplored. The studies reviewed here offer some initial insight into understanding how acute stress exposure affects the inhibition and control of conditioned fear. The research discussed in this review used Pavlovian fear conditioning as TAM Receptor inhibitor a basis for understanding the effects of stress on the regulation of fear. Since the neural circuitry underlying fear learning is highly

conserved across species, we can use Epigenetics inhibitor animal models as a basis for understanding how stress may influence this circuitry in humans as well. Our investigation of extinction and cognitive regulation reveals robust effects of stress impairing the persistent inhibition of fear, presumably by altering prefrontal cortex function. Although less is known concerning the impact of stress on the persistent fear reduction observed with avoidance and reconsolidation, it is possible these fear regulation techniques are less vulnerable to the negative consequences of stress since they rely less on the inhibitory mechanisms involved in extinction and cognitive regulation. It is important to note that the behavioral and neural research covered in this review focused mainly on brief exposure to stress, rather

than chronic exposure. Although the immediate effects of acute stress can exert detrimental effects on the brain regions critical to the regulation of fear responses, chronic exposure to stress can trigger to more systemic neuroendocrine changes. For example, chronic stress can lead to dysfunctional regulation of the HPA-axis, resulting in a flattened diurnal cycle of cortisol release, such as that seen in depressives and PTSD (Young et al., 1994; Yehuda, 2009). It can also lead to more profound structural Idoxuridine and functional changes in brain regions critical to autonomic and HPA-axis related regulation (i.e., amygdala and hippocampus) that can lead to suppression of synaptic plasticity and neurogenesis in these regions (see McEwen, 2003 for review). Collectively, chronic stress produces what has referred to as allostatic load, creating an overwhelming demand on the neural circuits that mediate appropriate responses and recovery from stress. Fear learning and regulation is a prominent model for describing the pathogenesis of anxiety disorders and stress-related psychopathology.