Author(s): Ludger Elling 1 , * , Harald Schupp 2 , Janine Bayer 3 , Ann-Kathrin Bröckelmann 1 , Christian Steinberg 1 , Christian Dobel 1 , Markus Junghofer 1
It has been suggested that, under acute stress, the allocation of attention becomes more automatic and less controlled , . A rationale for this suggestion may be derived from a neurobiological perspective. Acute stress elicits a variety of stress responses that can affect attention.
Beyond the stress-induced secretion of glucocorticoids (HPA-response), central chatecholaminergic stress responses (CCR) have been discussed in recent times. One aspect of the CCR is the activation of ascending noradrenergic projections emanating from the locus coeruleus (LC-NE) and the lateral tegmental field . A stress-induced increase in the tonic activity of LC-NE has been demonstrated in a number of animal studies using a variety of stressors . In fact, the LC is one of the most stress-sensitive structures in the brain  and, together with the paraventricular nucleus, plays a pivotal role in governing the stress responses.
The LC-NE system is also involved in attention. Specifically, it inhibits spontaneous orienting responses to distracting stimuli and prevents them from disrupting volitionally focused attention . Cortical areas that play a role in spontaneous orienting responses to distractors ,  receive inhibiting phasic input from the LC-NE (see , for a review). An increased tonic LC-NE activity may impair this inhibiting phasic input . It is thus plausible that, under acute stress, distractibility is increased and directed attention is impaired , .
This proposal, however, is largely based on rodent models . In humans, anecdotal evidence from pharmacological practice prevails and there is a lack of controlled trials , . The present work intended to substantiate the influence of CCR on two distinct functions of visual attention: namely, emotional attention and exogenous attention. MEG correlates of both respective functions were observed under a state of acute anticipatory stress and compared with a euthymic state.
As a general working hypothesis, we propose that, under anticipatory stress, the direction of attention may be shifted away away from a volitionally controlled direction towards a more spontaneously triggered direction. In terms of experimental operationalization, task-irrelevant but significant stimuli may detract a share of the perceptual resources from task-relevant stimulation in the sense of a biased competion , . We expect this biased competition to be reflected by electrophysiological correlates of exogenous attention  and also to be reflected by correlates of emotional attention , respectively.
The term "exogenous attention" is defined as attention that is captured by the intrusive salience of an external stimulus . The stimulus salience is usually based on its sudden onset, change or movement within the visual scene , , or by some other kind of deviance in an otherwise homogeneous stimulus environment. As a common example, flickering banner ads on the Internet exploit this effect.
The macroanatomical circuitry of exogenous attention involves cortico-cortical associations; in particular, associations that emanate from the right temporoparietal junction and the...