Department of Psychology, Carnegie Mellon University, Pittsburgh, PA, USA.
Neuroimage. 2011 Mar 15;55(2):763-72. doi: 10.1016/j.neuroimage.2010.12.034. Epub 2010 Dec 17.
The present neuroimaging study examines how repetition-related neural attenuation effects differ as a function of the perceptual similarity of the repetition and subsequent memory. One previous study (Turk-Browne et al., 2006) reported greater attenuation effects for subsequent hits than for misses. Another study (Wagner et al., 2000) found that neural attenuation is negatively correlated with subsequent memory. These opposing results suggest that repetition-related neural attenuation for subsequent hits and misses may be driven by different factors. In order to investigate the factors that affect the degree of neural attenuation, we varied perceptual similarity between repetitions in a scanned encoding phase that was followed by a subsequent memory test outside the scanner. We demonstrated that the degree of neural attenuation in the object processing regions depends on the interaction between perceptual similarity across repeated presentations and the quality their encodings. Specifically, the same areas that decreased neural signal for repetitions of same exemplars that were subsequently recognized with confidence that the repetitions were identical showed a decrease in neural signal for different-exemplar misses but not for the corresponding subsequently recognized hits. Our results imply that repetition-related neural attenuation should be related to the more efficient processing of perceptual properties of the stimuli only if subjects are able to subsequently remember the stimuli. Otherwise, the cause of attenuation may be in the failure to encode the stimuli on the second presentation as shown by the pattern of neural attenuation for the different-exemplar misses.
本神经影像学研究考察了重复相关的神经衰减效应如何随重复和后续记忆的知觉相似性而变化。一项先前的研究（Turk-Browne 等人，2006）报告说，后续命中的衰减效应大于后续错失。另一项研究（Wagner 等人，2000）发现神经衰减与后续记忆呈负相关。这些相反的结果表明，后续命中和错失的重复相关神经衰减可能是由不同的因素驱动的。为了研究影响神经衰减程度的因素，我们在扫描编码阶段改变了重复之间的知觉相似性，随后在扫描仪外进行了后续记忆测试。我们证明，物体处理区域的神经衰减程度取决于重复呈现之间的知觉相似性和其编码质量之间的相互作用。具体来说，对于相同范例的重复，其随后被自信地识别为相同，相同的区域会降低神经信号，但对于不同范例的错失，其神经信号不会降低，而对于相应的随后被识别为命中的情况则不会。我们的结果表明，只有当受试者能够随后记住刺激时，重复相关的神经衰减才应该与刺激的知觉属性的更有效处理有关。否则，衰减的原因可能是在第二次呈现时未能对刺激进行编码，这从不同范例错失的神经衰减模式中可以看出。
