Effects of anxiety on the antisaccade task were assessed. Performance effectiveness on this task (indexed by error rate) reflects a conflict between volitional and reflexive responses resolved by inhibitory processes (Hutton, S. B., & Ettinger, U. (2006). The antisaccade task as a research tool in psychopathology: A critical review. Psychophysiology, 43, 302-313). However, latency of the first correct saccade reflects processing efficiency (relationship between performance effectiveness and use of resources). In two experiments, high-anxious participants had longer correct antisaccade latencies than low-anxious participants and this effect was greater with threatening cues than positive or neutral ones. The high- and low-anxious groups did not differ in terms of error rate in the antisaccade task. No group differences were found in terms of latency or error rate in the prosaccade task. These results indicate that anxiety affects performance efficiency but not performance effectiveness. The findings are interpreted within the context of attentional control theory (Eysenck, M. W., Derakshan, N., Santos, R., & Calvo, M. G. (2007). Anxiety and cognitive performance: Attentional control theory. Emotion, 7 (2), 336-353).

There is behavioral evidence to show that anxiety is associated with an attentional bias for threat-related material (see Bar-Haim, Lamy, Pergamin, BakermansKranenburg, & van IJzendoorn, 2007, for a review). Recent neuroimaging work has also shown that anxiety selectively facilitates early processing of threat and enhances distractibility to task-irrelevant stimuli. According to Bishop (2007; see also Bishop, Duncan, Brett, & Lawrence, 2004), anxiety is associated with enhanced amygdala activation and reduced recruitment of prefrontal cortical areas (especially the dorsal lateral prefrontal cortex [DLPFC] and the ventral lateral prefrontal cortex [VLPFC]) that are heavily involved in top-down regulation of attention, especially when attentional focus is required for efficient task performance. Both behavioral and neuroimaging work has shown that anxiety is associated with adverse effects on cognitive performance, especially on tasks that require attentional focus. In an attempt to explain the role of attentional control in anxiety and cognitive performance, the attentional control theory of anxiety was put forward by Eysenck, Derakshan, Santos, and Calvo (2007).The attentional control theory (Eysenck et al., 2007) is a major development of processing efficiency theory (Eysenck & Calvo, 1992). Based on Baddeley's (1986; see also Derryberry & Reed, 2002) working memory model, the theory claims that anxiety disrupts the balance b between what Corbetta and Shulman (2002) distinguished as the stimulus-driven (involved in bottom-up control, influenced by salient environmental stimuli) and the goaldirected (involved in top-down control, influenced by the current goal) systems. These two systems are generally thought to interact in their functioning (Pashler, Johnston, & Ruthruff, 2001), but anxiety is believed to increase the influence of the stimulus-driven system over the goaldirected processes, reducing attentional control.Predictions of the attentional control theory are based on a fundamental distinction by the processing efficiency theory (Eysenck & Calvo, 1992) between performance ef-f f fectiveness and performance efficiency. Effectiveness refers to an individual's competence in doing a task (measured by f response accuracy), and efficiency refers to the amount of processing resources invested in doing the task (measured by response latency). The theory predicts that anxiety has a greater impact on performance efficiency of tasks requiring the inhibition ("one's ability to deliberately inhibit dominant, automatic, or prepotent responses when necessary"; Miyake et al., 2000, p. 57) and/or the shifting d ("shifting back and g forth between multiple tasks"; Miyake et al., 2000, p. 55) functions of the central executive. In inhibition, attentional d control prevents attentional resources from being allocated to task-irrelevant stimuli, and in shifting, attentional control is used in a positive way to allocate attentional resources to execute the task relevant to the current goal.A general assumption of the atten...

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IMPORTANCE Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) is under clinical investigation as a treatment for major depressive disorder. However, the mechanisms of action are unclear, and there is a lack of neuroimaging evidence, particularly among individuals with affective dysfunction. Furthermore, there is no direct causal evidence among humans that the prefrontal-amygdala circuit functions as described in animal models (ie, that increasing activity in prefrontal cortical control regions inhibits amygdala response to threat). OBJECTIVE To determine whether stimulation of the prefrontal cortex reduces amygdala threat reactivity in individuals with trait anxiety. DESIGN, SETTING, AND PARTICIPANTS This community-based randomized clinical trial used a double-blind, within-participants design (2 imaging sessions per participant). Eighteen women with high trait anxiety (age range, 18-42 years) who scored greater than 45 on the trait measure of State-Trait Anxiety Inventory were randomized to receive active or sham tDCS of the DLPFC during the first session and the other intervention during the next session. Each intervention was followed immediately by a functional imaging scan during which participants performed an attentional task requiring them to ignore threatening face distractors. Data were collected from May 7 to October 6, 2015. MAIN OUTCOMES AND MEASURES Amygdala threat response, measured with functional magnetic resonance imaging. RESULTS Data from 16 female participants (mean age, 23 years; range, 18-42 years), with 8 in each group, were analyzed. Compared with sham stimulation, active DLPFC stimulation significantly reduced bilateral amygdala threat reactivity (z = 3.30, P = .04) and simultaneously increased activity in cortical regions associated with attentional control (z = 3.28, P < .001). In confirmatory behavioral analyses, there was a mean improvement in task accuracy of 12.2% (95% CI, 0.30%-24.0%; mean [SD] difference in number of correct answers, 2.2 [4.5]; t 15 = 1.94, P = .04) after active DLPFC stimulation. CONCLUSIONS AND RELEVANCE These results reveal a causal role for prefrontal regulation of amygdala function in attentional capture by threat in individuals with high trait anxiety. The finding that prefrontal stimulation acutely increases attentional control signals and reduces amygdala threat reactivity may indicate a neurocognitive mechanism that could contribute to tDCS treatment effects in affective disorders.