National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
Soc Cogn Affect Neurosci. 2011 Oct;6(5):537-47. doi: 10.1093/scan/nsq079. Epub 2010 Oct 7.
Adolescents spend a significant part of their leisure time watching TV programs and movies that portray violence. It is unknown, however, how the extent of violent media use and the severity of aggression displayed affect adolescents' brain function. We investigated skin conductance responses, brain activation and functional brain connectivity to media violence in healthy adolescents. In an event-related functional magnetic resonance imaging experiment, subjects repeatedly viewed normed videos that displayed different degrees of aggressive behavior. We found a downward linear adaptation in skin conductance responses with increasing aggression and desensitization towards more aggressive videos. Our results further revealed adaptation in a fronto-parietal network including the left lateral orbitofrontal cortex (lOFC), right precuneus and bilateral inferior parietal lobules, again showing downward linear adaptations and desensitization towards more aggressive videos. Granger causality mapping analyses revealed attenuation in the left lOFC, indicating that activation during viewing aggressive media is driven by input from parietal regions that decreased over time, for more aggressive videos. We conclude that aggressive media activates an emotion-attention network that has the capability to blunt emotional responses through reduced attention with repeated viewing of aggressive media contents, which may restrict the linking of the consequences of aggression with an emotional response, and therefore potentially promotes aggressive attitudes and behavior.
青少年会将大量闲暇时间用于观看描绘暴力的电视节目和电影。然而，目前尚不清楚过度观看暴力媒体以及所展示的攻击行为的严重程度会如何影响青少年的大脑功能。我们研究了健康青少年对媒体暴力的皮肤电反应、大脑激活和功能连接。在一项基于事件的功能磁共振成像实验中，受测者反复观看了展示不同程度攻击行为的标准化视频。我们发现，随着攻击行为的增加和对更具攻击性的视频的脱敏，皮肤电反应呈下降的线性适应。我们的结果进一步揭示了包括左侧眶额外侧皮质（lOFC）、右侧顶内小叶和双侧顶下小叶在内的额顶叶网络的适应，同样显示出对更具攻击性的视频的下降线性适应和脱敏。格兰杰因果关系映射分析显示左侧 lOFC 的抑制，表明在观看攻击性行为的媒体时的激活是由来自顶叶区域的输入驱动的，随着时间的推移，这些输入会减少，对于更具攻击性的视频则更是如此。我们的结论是，攻击性媒体激活了一个情绪注意网络，通过重复观看攻击性媒体内容，减少注意力，从而有可能削弱对攻击行为后果的情绪反应，因此可能会促进攻击性态度和行为。
