Author(s): Ludger Elling 1 , * , Harald Schupp 2 , Janine Bayer 3 , Ann-Kathrin Bröckelmann 1 , Christian Steinberg 1 , Christian Dobel 1 , Markus Junghofer 1
Introduction
It has been suggested that, under acute stress, the allocation of attention becomes more automatic and less controlled [1], [2]. 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 [3]. 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 [4]. In fact, the LC is one of the most stress-sensitive structures in the brain [5] 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 [6]. Cortical areas that play a role in spontaneous orienting responses to distractors [7], [8] receive inhibiting phasic input from the LC-NE (see [9], for a review). An increased tonic LC-NE activity may impair this inhibiting phasic input [6]. It is thus plausible that, under acute stress, distractibility is increased and directed attention is impaired [4], [9].
This proposal, however, is largely based on rodent models [10]. In humans, anecdotal evidence from pharmacological practice prevails and there is a lack of controlled trials [3], [11]. 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 [12], [13]. We expect this biased competition to be reflected by electrophysiological correlates of exogenous attention [14] and also to be reflected by correlates of emotional attention [15], respectively.
Exogenous Attention
The term "exogenous attention" is defined as attention that is captured by the intrusive salience of an external stimulus [16]. The stimulus salience is usually based on its sudden onset, change or movement within the visual scene [17], [18], 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...