Phillips Mary L, Williams Leanne M, Heining Maike, Herba Catherine M, Russell Tamara, Andrew Christopher, Bullmore Ed T, Brammer Michael J, Williams Steven C R, Morgan Michael, Young Andrew W, Gray Jeffrey A
Section of Neuroscience and Emotion, Department of Psychological Medicine, Institute of Psychiatry, KCL, London, UK.
Neuroimage. 2004 Apr;21(4):1484-96. doi: 10.1016/j.neuroimage.2003.12.013.
There is debate in cognitive neuroscience whether conscious versus unconscious processing represents a categorical or a quantitative distinction. The purpose of the study was to explore this matter using functional magnetic resonance imaging (fMRI). We first established objective thresholds of the critical temporal parameters for overt and covert presentations of fear and disgust. Next we applied these stimulus parameters in an fMRI experiment to determine whether non-consciously perceived (covert) facial expressions of fear and disgust show the same double dissociation (amygdala response to fear, insula to disgust) observed with consciously perceived (overt) stimuli. A backward masking paradigm was used. In the psychophysics experiment, the following parameters were established: 30-ms target duration for the covert condition, and 170-ms target duration for the overt condition. Results of the block-design fMRI study indicated substantial differences underlying the perception of fearful and disgusted facial expressions, with significant effects of both emotion and target duration. Findings for the overt condition (170 ms) confirm previous evidence of amygdala activation to fearful faces, and insula activation to disgusted faces, and a double dissociation between these two emotions. In the covert condition (30 ms), the amygdala was not activated to fear, nor was the insula activated to disgust. Overall, findings demonstrate significant differences between the neural responses to fear and to disgust, and between the covert presentations of these two emotions. These results therefore suggest distinct neural correlates of conscious and unconscious emotion perception.
有意识加工与无意识加工究竟代表着一种类别上的区分还是数量上的差异。本研究的目的是使用功能磁共振成像（fMRI）来探究这一问题。我们首先确定了恐惧和厌恶的外显与内隐呈现的关键时间参数的客观阈值。接下来，我们在一项fMRI实验中应用这些刺激参数，以确定无意识感知（内隐）的恐惧和厌恶面部表情是否显示出与有意识感知（外显）刺激时观察到的相同的双重分离（杏仁核对恐惧有反应，脑岛对厌恶有反应）。我们采用了反向掩蔽范式。在心理物理学实验中，确定了以下参数：内隐条件下目标持续时间为30毫秒，外显条件下目标持续时间为170毫秒。组块设计fMRI研究的结果表明，恐惧和厌恶面部表情的感知存在显著差异，情绪和目标持续时间均有显著影响。外显条件（170毫秒）的研究结果证实了先前关于杏仁核对恐惧面孔激活、脑岛对厌恶面孔激活以及这两种情绪之间双重分离的证据。在内隐条件（30毫秒）下，杏仁核对恐惧未被激活，脑岛对厌恶也未被激活。总体而言，研究结果表明对恐惧和厌恶的神经反应之间以及这两种情绪的内隐呈现之间存在显著差异。因此，这些结果表明有意识和无意识情绪感知具有不同的神经关联。
