Section on Development and Affective Neuroscience, National Institute of Mental Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
J Child Psychol Psychiatry. 2012 Jun;53(6):678-86. doi: 10.1111/j.1469-7610.2011.02503.x. Epub 2011 Dec 3.
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.
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.
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.
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.
在焦虑障碍患者中，常可检测到对威胁的注意力偏向。通过点探测范式可以在实验中测量威胁偏向，在该范式中，个体在包括威胁的刺激对之后检测探针。在这些任务中，焦虑个体对先前被威胁占据的位置（即一致条件）出现的探针的检测速度快于相反威胁（即不一致条件）出现的探针。在儿科焦虑障碍中，点探测范式可检测到对威胁的异常注意力偏向和异常腹外侧前额叶皮层（vlPFC）功能。然而，尚不清楚这种异常的 vlPFC 激活是在个体处理威胁（例如生气的面孔）时发生，还是在处理和响应探针时发生。这项脑磁图（MEG）研究旨在回答这个问题。
患有广泛性焦虑障碍（GAD，n=17）或无精神科诊断（n=25）的青少年执行涉及生气和中性面孔的点探测任务，同时采集 MEG 数据。使用合成孔径磁图（SAM）波束形成技术来确定在个体处理威胁（即生气与中性面孔）或在个体响应不一致与一致探针时，是否存在组间功率比差异。
在 1-30Hz 的频率带中出现了反应期时 vlPFC 激活的组间差异。在响应生气面孔线索时，未检测到 vlPFC 激活的组间差异。
在点探测任务中，vlPFC 激活的与焦虑相关的扰动反映了在响应与行为相关探针时的异常注意力控制，而不是对生气面孔的反应。鉴于这些探针的运动反应用于计算威胁偏向，本研究为这一常用于焦虑标志物的异常提供了对病理生理学的深入了解。此外，这一发现可能为靶向 vlPFC 以增强对任务相关需求的注意力控制的新型焦虑障碍治疗方法的开发提供信息。
