King Danielle R, Schubert Misty L, Miller Michael B
Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, USA,
Cogn Affect Behav Neurosci. 2015 Sep;15(3):662-79. doi: 10.3758/s13415-015-0357-4.
Regions of the lateral posterior parietal cortex (PPC) tend to be more active during recognition of previously studied items compared to correct rejection of unstudied items. Previously, we demonstrated that this effect is source-specific. While items that were encoded through visual perception elicited robust successful retrieval activity in the lateral PPC during a subsequent source memory test, items that were visually imagined did not elicit this effect. Memories of perceived events typically contain more perceptually-based contextual details than memories of imagined events. Therefore, source-based differences in lateral parietal activity might be due to a difference in the perceptual vividness of memories of perceived and imagined events. The goal of the present study was to test this hypothesis. Participants perceived and imagined items in both high and low perceptual vividness conditions. Experiment 1 demonstrated that memories for items encoded in the high vividness conditions contained significantly greater visual detail than memories encoded in the low vividness conditions. In Experiment 2, participants were scanned while they made source memory judgments about items that were previously perceived and imagined in high and low vividness conditions. Consistent with previous findings, the left lateral PPC was more active during retrieval of perceived compared to imagined events. However, lateral PPC activity did not vary according to vividness, suggesting that source effects in this region cannot be explained by a difference in the perceptual vividness of memories encoded through perception versus imagination.
与正确拒绝未学习项目相比，在识别先前学习的项目时，外侧顶叶后皮质（PPC）区域往往更活跃。此前，我们证明了这种效应是源特异性的。在随后的源记忆测试中，通过视觉感知编码的项目在外侧PPC中引发了强烈的成功检索活动，而通过视觉想象编码的项目则没有引发这种效应。感知事件的记忆通常比想象事件的记忆包含更多基于感知的情境细节。因此，外侧顶叶活动中基于源的差异可能是由于感知事件和想象事件记忆的感知生动性差异所致。本研究的目的是检验这一假设。参与者在高感知生动性和低感知生动性条件下对项目进行感知和想象。实验1表明，在高生动性条件下编码的项目记忆比在低生动性条件下编码的项目记忆包含显著更多的视觉细节。在实验2中，参与者在对先前在高生动性和低生动性条件下感知和想象的项目进行源记忆判断时接受扫描。与先前的研究结果一致，与想象事件相比，在检索感知事件时左侧外侧PPC更活跃。然而，外侧PPC的活动并没有因生动性而变化，这表明该区域的源效应不能用通过感知与想象编码的记忆的感知生动性差异来解释。
