欲望的神经机制及美学价值

The Neural Correlates of Desire

在事件相关的功能性核磁共振成像(fMRI)研究中,本实验扫描了18位正在观看三类图片(事件、事物和人物)并依据其欲望强度(可欲的、一般的、不可欲的)对图片进行分类的正常人类受试者。每种类别的图片都将激活视觉脑的特定区域,因而反映出其功能专属区。研究采用合取分析来探究是否存在一个大脑区域,当一个可欲的图片被观看时该区域始终保持活跃,而与图片所属的类别无关。“可欲的>不可欲的”对比的合取分析揭示了眶额皮层上部①的活动。这一活动与受试者报告的可欲强度层级成正相关的线性关系。“可欲的>一般的”这组的合取分析显示了中扣带皮层与前扣带皮层的活动。在前者中,可欲与不可欲的刺激物引发的活跃度比一般的刺激物引发的活跃度更强烈。其他的合取分析并没有产生明显效果。这些结果表明,根据欲望强度对任何刺激物进行分类的行为都会激活三个不同的脑区:眶额皮层上部、中扣带皮层和前扣带皮层。

In an event-related fMRI study,we scanned eighteen normal human subjects while they viewed three categories of pictures(events,objects and persons)which are classified according to desirability(desirable,indifferent or undesirable).Each category produced an activity in a distinct part of the visual brain,thus reflecting its functional specialization.We used conjunction analysis to learn whether there is a brain area which is always active when a desirable picture is viewed,regardless of the category to which it belongs.The conjunction analysis of the contrast“desirable>undesirable”revealed activity in the superior orbito-frontal cortex.This activity bore a positive linear relationship to the declared level of desirability.The conjunction analysis of"desirable>indifferent"revealed activity in the mid-cingulate cortex and in the anterior cingulate cortex.In the former,the activity induced by desirable and undesirable stimuli is stronger than the activity induced by general stimuli classified as indifferent.Other conjunction analyses produced no significant effects.These results show that categorizing any stimulus according to its desirability activates three different areas of brain:the superior orbito-frontal,the mid-cingulate,and the anterior cingulate cortices.