Mooshagian Eric, Kaplan Jonas, Zaidel Eran, Iacoboni Marco
Department of Psychology, University of California Los Angeles, Los Angeles, California, United States of America.
PLoS One. 2008 Jun 4;3(6):e2348. doi: 10.1371/journal.pone.0002348.
Parallel processing of multiple sensory stimuli is critical for efficient, successful interaction with the environment. An experimental approach to studying parallel processing in sensorimotor integration is to examine reaction times to multiple copies of the same stimulus. Reaction times to bilateral copies of light flashes are faster than to single, unilateral light flashes. These faster responses may be due to 'statistical facilitation' between independent processing streams engaged by the two copies of the light flash. On some trials, however, reaction times are faster than predicted by statistical facilitation. This indicates that a neural 'coactivation' of the two processing streams must have occurred. Here we use fMRI to investigate the neural locus of this coactivation. Subjects responded manually to the detection of unilateral light flashes presented to the left or right visual hemifield, and to the detection of bilateral light flashes. We compared the bilateral trials where subjects' reaction times exceeded the limit predicted by statistical facilitation to bilateral trials that did not exceed the limit. Activity in the right temporo-parietal junction was higher in those bilateral trials that showed coactivation than in those that did not. These results suggest the neural coactivation observed in visuomotor integration occurs at a cognitive rather than sensory or motor stage of processing.
对多种感觉刺激进行并行处理对于与环境进行高效、成功的交互至关重要。研究感觉运动整合中并行处理的一种实验方法是检查对同一刺激的多个副本的反应时间。对双侧闪光副本的反应时间比对单个单侧闪光的反应时间更快。这些更快的反应可能是由于闪光的两个副本所涉及的独立处理流之间的“统计促进”。然而，在某些试验中，反应时间比统计促进所预测的要快。这表明两个处理流必定发生了神经“共同激活”。在此，我们使用功能磁共振成像来研究这种共同激活的神经位点。受试者对呈现于左或右视觉半视野的单侧闪光的检测以及对双侧闪光的检测进行手动反应。我们将受试者反应时间超过统计促进所预测极限的双侧试验与未超过该极限的双侧试验进行了比较。在那些显示共同激活的双侧试验中，右侧颞顶联合区的活动高于未显示共同激活的试验。这些结果表明，在视觉运动整合中观察到的神经共同激活发生在认知阶段而非感觉或运动处理阶段。
