Cecere Roberto, Bertini Caterina, Maier Martin E, Làdavas Elisabetta
Università of Bologna, Bologna, Italy.
J Cogn Neurosci. 2014 Nov;26(11):2564-77. doi: 10.1162/jocn_a_00671. Epub 2014 Jun 4.
Visual threat-related signals are not only processed via a cortical geniculo-striatal pathway to the amygdala but also via a subcortical colliculo-pulvinar-amygdala pathway, which presumably mediates implicit processing of fearful stimuli. Indeed, hemianopic patients with unilateral damage to the geniculo-striatal pathway have been shown to respond faster to seen happy faces in their intact visual field when unseen fearful faces were concurrently presented in their blind field [Bertini, C., Cecere, R., & Làdavas, E. I am blind, but I "see" fear. Cortex, 49, 985-993, 2013]. This behavioral facilitation in the presence of unseen fear might reflect enhanced processing of consciously perceived faces because of early activation of the subcortical pathway for implicit fear perception, which possibly leads to a modulation of cortical activity. To test this hypothesis, we examined ERPs elicited by fearful and happy faces presented to the intact visual field of right and left hemianopic patients, whereas fearful, happy, or neutral faces were concurrently presented in their blind field. Results showed that the amplitude of the N170 elicited by seen happy faces was selectively increased when an unseen fearful face was concurrently presented in the blind field of right hemianopic patients. These results suggest that when the geniculo-striate visual pathway is lesioned, the rapid and implicit processing of threat signals can enhance facial encoding. Notably, the N170 modulation was only observed in left-lesioned patients, favoring the hypothesis that implicit subcortical processing of fearful signals can influence face encoding only when the right hemisphere is intact.
与视觉威胁相关的信号不仅通过皮质膝状体 - 纹状体通路传输至杏仁核，还通过皮质下的中脑顶盖 - 丘脑枕 - 杏仁核通路进行传输，该通路可能介导对恐惧刺激的隐性处理。事实上，已有研究表明，膝状体 - 纹状体通路单侧受损的偏盲患者，当在其盲视野中同时呈现未被看到的恐惧面孔时，他们对在其完整视野中看到的开心面孔的反应会更快[贝尔蒂尼，C.，切切雷，R.，& 拉达瓦斯，E. 我失明了，但我“看到”了恐惧。《皮质》，49，985 - 993，2013]。在未被看到的恐惧存在时的这种行为促进作用，可能反映了由于隐性恐惧感知的皮质下通路的早期激活，从而增强了对有意识感知面孔的处理，这可能导致皮质活动的调节。为了验证这一假设，我们检测了向左右偏盲患者的完整视野呈现恐惧和开心面孔时诱发的事件相关电位（ERP），而在他们的盲视野中同时呈现恐惧、开心或中性面孔。结果显示，当在右偏盲患者的盲视野中同时呈现未被看到的恐惧面孔时，看到的开心面孔诱发的N170波幅会选择性增加。这些结果表明，当膝状体 - 纹状视觉通路受损时，威胁信号的快速和隐性处理可以增强面部编码。值得注意的是，仅在左侧受损的患者中观察到了N170的调制，这支持了这样一种假设，即只有当右半球完整时，恐惧信号的隐性皮质下处理才能影响面部编码。
