Pessoa Luiz, Ungerleider Leslie G
Department of Psychology, Brown University, Providence, RI 02912, USA.
Cereb Cortex. 2004 May;14(5):511-20. doi: 10.1093/cercor/bhh013. Epub 2004 Mar 28.
Detecting changes in an ever-changing environment is highly advantageous, and this ability may be critical for survival. In the present study, we investigated the neural substrates of change detection in the context of a visual working memory task. Subjects maintained a sample visual stimulus in short-term memory for 6 s, and were asked to indicate whether a subsequent, test stimulus matched or did not match the original sample. To study change detection largely uncontaminated by attentional state, we compared correct change and correct no-change trials at test. Our results revealed that correctly detecting a change was associated with activation of a network comprising parietal and frontal brain regions, as well as activation of the pulvinar, cerebellum, and inferior temporal gyrus. Moreover, incorrectly reporting a change when none occurred led to a very similar pattern of activations. Finally, few regions were differentially activated by trials in which a change occurred but subjects failed to detect it (change blindness). Thus, brain activation was correlated with a subject's report of a change, instead of correlated with the physical change per se. We propose that frontal and parietal regions, possibly assisted by the cerebellum and the pulvinar, might be involved in controlling the deployment of attention to the location of a change, thereby allowing further processing of the visual stimulus. Visual processing areas, such as the inferior temporal gyrus, may be the recipients of top-down feedback from fronto-parietal regions that control the reactive deployment of attention, and thus exhibit increased activation when a change is reported (irrespective of whether it occurred or not). Whereas reporting that a change occurred, be it correctly or incorrectly, was associated with strong activation in fronto-parietal sites, change blindness appears to involve very limited territories.
在不断变化的环境中检测变化具有很大优势，这种能力可能对生存至关重要。在本研究中，我们在视觉工作记忆任务的背景下研究了变化检测的神经基础。受试者在短期记忆中保持一个样本视觉刺激6秒，并被要求指出随后的测试刺激是否与原始样本匹配或不匹配。为了研究在很大程度上不受注意力状态影响的变化检测，我们在测试时比较了正确变化和正确无变化试验。我们的结果表明，正确检测到变化与包括顶叶和额叶脑区的网络激活以及丘脑枕、小脑和颞下回的激活有关。此外，在没有变化时错误地报告有变化会导致非常相似的激活模式。最后，在发生了变化但受试者未能检测到（变化盲视）的试验中，很少有区域被差异激活。因此，大脑激活与受试者对变化的报告相关，而不是与实际变化本身相关。我们提出，额叶和顶叶区域可能在小脑和丘脑枕的协助下，参与控制将注意力部署到变化的位置，从而允许对视觉刺激进行进一步处理。视觉处理区域，如颞下回，可能是来自控制注意力反应性部署的额顶叶区域的自上而下反馈的接受者，因此在报告有变化时（无论变化是否实际发生）会表现出激活增加。虽然报告有变化，无论正确与否，都与额顶叶部位的强烈激活有关，但变化盲视似乎只涉及非常有限的区域。
