• magnetoencephalography;
  • ventrolateral prefrontal cortex;
  • attention

Background:  Attention biases toward threat are often detected in individuals with anxiety disorders. Threat biases can be measured experimentally through dot-probe paradigms, in which individuals detect a probe following a stimulus pair including a threat. On these tasks, individuals with anxiety tend to detect probes that occur in a location previously occupied by a threat (i.e., congruent) faster than when opposite threats (i.e., incongruent). In pediatric anxiety disorders, dot-probe paradigms detect abnormal attention biases toward threat and abnormal ventrolateral prefrontal cortex (vlPFC) function. However, it remains unclear if this aberrant vlPFC activation occurs while subjects process threats (e.g., angry faces) or, alternatively, while they process and respond to probes. This magnetoencephalography (MEG) study was designed to answer this question.

Methods:  Adolescents with either generalized anxiety disorder (GAD, n = 17) or no psychiatric diagnosis (n = 25) performed a dot-probe task involving angry and neutral faces while MEG data were collected. Synthetic Aperture Magnetometry (SAM) beamformer technique was used to determine whether there were group differences in power ratios while subjects processed threats (i.e., angry vs. neutral faces) or when subjects responded to incongruent versus. congruent probes.

Results:  Group differences in vlPFC activation during the response period emerged with a 1–30 Hz frequency band. No group differences in vlPFC activation were detected in response to angry-face cues.

Conclusions:  In the dot-probe task, anxiety-related perturbations in vlPFC activation reflect abnormal attention control when responding to behaviorally relevant probes, but not to angry faces. Given that motor responses to these probes are used to calculate threat bias, this study provides insight into the pathophysiology reflected in this commonly used marker of anxiety. In addition, this finding may inform the development of novel anxiety-disorder treatments targeting the vlPFC to enhance attention control to task-relevant demands.