Tel Aviv University, Israel.
J Cogn Neurosci. 2010 Oct;22(10):2263-75. doi: 10.1162/jocn.2009.21402.
Interpretation of emotional context is a pivotal aspect of understanding social situations. A critical component of this process is assessment of danger levels in the surrounding, which may have a direct effect on the organism's survival. The limbic system has been implicated in mediating this assessment. In situations of uncertainty, the evaluation process may also call for greater involvement of prefrontal cortex for decision-making and planning of an appropriate behavioral response. In the following study, morphed face images depicting emotional expressions were used to examine brain correlates of subjective uncertainty and perceptual ambiguity regarding danger. Fear and neutral expressions of 20 faces were morphed, and each of the face videos was divided into three sequences of equal length representing three levels of objective certainty regarding the expressions neutral, fear, and ambiguous. Sixteen subjects were scanned in a 1.5-T scanner while viewing 60 x 6-sec video sequences and were asked to report their subjective certainty regarding the level of danger surrounding the face on a four-level scale combining definite/maybe and danger/no-danger values. The individual responses were recorded and used as the basis for a "subjective protocol" versus an "objective protocol." Significant activations of the amygdala, dorsomedial prefrontal cortex, and dorsolateral prefrontal cortex were observed under the subjective protocol of internally driven uncertainty, but not under objective stimuli-based ambiguity. We suggest that this brain network is involved in generating subjective assessment of social affective cues. This study provides further support to the "relevance detector" theory of the amygdala and implicates its importance to behavior relying heavily on subjective assessment of danger, such as in the security domain context.
情绪语境的解读是理解社交情境的关键方面。这个过程的一个关键组成部分是评估周围环境的危险程度，这可能直接影响到生物体的生存。边缘系统被认为在调节这种评估中起着重要作用。在不确定的情况下，评估过程也可能需要前额叶皮层更多地参与，以做出决策并规划适当的行为反应。在下面的研究中，使用变形人脸图像来研究主观不确定性和对危险的感知模糊的大脑相关物。20 张人脸的恐惧和中性表情被变形，每个人脸视频被分为三个相等长度的序列，分别代表表情中性、恐惧和模糊的三个客观确定性水平。16 名被试在 1.5T 扫描仪中观看 60 个 6 秒的视频序列，同时被要求在一个四等级量表上报告他们对人脸周围危险水平的主观确定性，该量表结合了确定/也许和危险/无危险的值。个体的反应被记录下来，并作为“主观协议”与“客观协议”的基础。在内部驱动的不确定性的主观协议下，观察到杏仁核、背内侧前额叶皮层和背外侧前额叶皮层的显著激活，但在基于客观刺激的模糊性下则没有。我们认为，这个大脑网络参与了对社会情感线索的主观评估。这项研究为杏仁核的“相关性探测器”理论提供了进一步的支持，并暗示其对严重依赖主观危险评估的行为的重要性，例如在安全领域的背景下。
