Connecting Brain and Behavior in the Very Brief Exposure Effect

描述（由申请人提供）：拟议研究的目标是对恐惧可以在没有意识的情况下减少的假设进行迄今为止最严格的测试。为了研究减少无意识恐惧的新过程及其潜在的实用价值，两个实验将从大脑和行为方面验证这一假设。这一假设挑战了流行的临床信念，即恐惧的对象必须直接面对充分的意识，以减少对它的恐惧。实验范例，非常短的曝光，包括一系列连续的向后掩蔽的恐惧图像（每个持续时间为33毫秒）。一系列实验表明，VBE减少了对恐惧物体的回避（Siegel, Anderson & Han, 2011; Weinberger, et al., 2011; Siegel & Weinberger, 2009），比同样刺激的清晰可见暴露（CVE）更有效（Siegel & Weinberger, 2012），并且这种减少回避的效果至少持续一年（Siegel & Warren, in press）。通过功能磁共振成像和行为实验来确定VBE的学习机制，并将其与恐惧回避的影响联系起来。功能磁共振实验将在纽约州精神病学研究所的磁共振实验室进行。研究人员将从纽约州立大学普斯学院的文科和理科课程中招募26名蜘蛛恐惧症患者和26名非蜘蛛恐惧症患者，使用广泛使用的问卷调查、行为回避测试（BAT）和DSM-IV诊断的结构化临床访谈。三种曝光类型中的每一种都将在受试者中进行：非常简短（33.4 ms SOA）和清晰可见（119 ms SOA）的蜘蛛图像，以及非常简短的花朵图像（对照组）。主观恐惧会在整个过程中周期性地进行评估。在没有恐惧经历的情况下，VBE有望使杏仁核激活习惯化，而CVE不会使恐惧反应习惯化，并诱发主观恐惧。行为实验将在纽约州立大学珀克斯学院的首席研究员实验室进行。80名蜘蛛恐惧症参与者——26名来自功能磁共振成像实验，74名来自其他实验——将以同样的方式被招募。基于对活狼蛛的基线回避水平，他们将被随机分配到非常短的（33毫秒SOA）蜘蛛或花的图像（对照组）。这些暴露将连续三周进行一次，然后在体内暴露于活的狼蛛。主观恐惧将在这些暴露之前和之后进行测量。在fMRI实验中，VBE对杏仁核激活的减少将预测对狼蛛的躲避减少。在第一次训练后，VBE将减少对活狼蛛的回避。对照组的参与者直到体内暴露的第三阶段才会获得相同的增益。随后的两个VBE会议将导致进一步的收益。该研究将为R01提案奠定基础，以进一步研究极短暴露的神经生物学机制并测试其对临床人群的影响。

DESCRIPTION (provided by applicant): The goal of the proposed research is to conduct the strictest test to date of the hypothesis that fear can be reduced without awareness. Two experiments will test this hypothesis with respect to brain and behavior in order to investigate novel processes of non-conscious fear reduction and their potential practical utility. This hypothesis challenges the prevailing clinical belief that a feared object must be directly confronted with full awareness in order to reduce fear of it. The experimental paradigm, very brief exposure, consists of a continuous series of backward masked phobic images (each for duration of 33-ms). A series of experiments has shown that VBE reduces avoidance of a feared object (Siegel, Anderson & Han, 2011; Weinberger, et al., 2011; Siegel & Weinberger, 2009), more than clearly visible exposure (CVE) to the same stimuli does (Siegel & Weinberger, 2012), and that the avoidance- reducing effect lasts for at least a year (Siegel & Warren, in press). An fMRI and behavioral experiment are designed to identify the learning mechanisms of VBE and link them to its effect on phobic avoidance. The fMRI experiment will be conducted at the MRI Laboratory of the New York State Psychiatric Institute. Twenty-six spider-phobic and twenty-six non-phobic participants will be recruited from liberal arts and science courses at Purchase College/SUNY with a widely used questionnaire, a Behavioral Avoidance Test (BAT), and the Structured Clinical Interview for DSM-IV Diagnosis. Each of three types of exposure will be administered within-subjects: very brief (33.4-ms SOA) and clearly visible (119-ms SOA) images of spiders, and very brief images of flowers (control). Subjective fear is rated periodically throughout. VBE is expected to habituate amygdala activation in the absence of the experience of fear, whereas CVE will not habituate fear responses and induce subjective fear. The behavioral experiment will be conducted in the Principal Investigator's lab at Purchase College/SUNY. 80 spider-phobic participants - 26 from the fMRI experiment, and 74 others - will be recruited in the same manner. Based on baseline levels of avoidance of a live tarantula, they will be randomly assigned to exposure to very brief (33-ms SOA) images of either spiders or flowers (control group). These exposures will be administered each of three consecutive weeks, followed by in vivo exposure to a live tarantula. Subjective fear will be measured just before and after these exposures. Reduction of amygdala activation by VBE in the fMRI experiment will predict reduction of avoidance of the tarantula. VBE will reduce avoidance of a live tarantula after the first session. Control participants will not make the same gain until the 3rd session of n vivo exposure. The two subsequent VBE sessions will result in further gains. The proposed research will lay the groundwork for an R01 Proposal to further investigate neurobiological mechanisms of very brief exposure and test its effects on clinical populations.