Rotman Research Institute at Baycrest, Toronto, Ontario, Canada M6A 2E1, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, Texas 75080-3021, and Department of Psychology, University of Toronto, Toronto, Ontario, Canada, M5S 3G3.
J Neurosci. 2014 Mar 19;34(12):4175-86. doi: 10.1523/JNEUROSCI.3054-13.2014.
We investigated how aging affects the neural specificity of mental replay, the act of conjuring up past experiences in one's mind. We used functional magnetic resonance imaging (fMRI) and multivariate pattern analysis to quantify the similarity between brain activity elicited by the perception and memory of complex multimodal stimuli. Young and older human adults viewed and mentally replayed short videos from long-term memory while undergoing fMRI. We identified a wide array of cortical regions involved in visual, auditory, and spatial processing that supported stimulus-specific representation at perception as well as during mental replay. Evidence of age-related dedifferentiation was subtle at perception but more salient during mental replay, and age differences at perception could not account for older adults' reduced neural reactivation specificity. Performance on a post-scan recognition task for video details correlated with neural reactivation in young but not in older adults, indicating that in-scan reactivation benefited post-scan recognition in young adults, but that some older adults may have benefited from alternative rehearsal strategies. Although young adults recalled more details about the video stimuli than older adults on a post-scan recall task, patterns of neural reactivation correlated with post-scan recall in both age groups. These results demonstrate that the mechanisms supporting recall and recollection are linked to accurate neural reactivation in both young and older adults, but that age affects how efficiently these mechanisms can support memory's representational specificity in a way that cannot simply be accounted for by degraded sensory processes.
我们研究了衰老如何影响心理再激活的神经特异性，即在脑海中唤起过去经历的行为。我们使用功能磁共振成像（fMRI）和多元模式分析来量化复杂多模态刺激的感知和记忆所引起的大脑活动之间的相似性。年轻和年长的成年人类参与者在进行 fMRI 扫描的同时观看和在脑海中重新播放来自长期记忆的短视频。我们确定了广泛的皮质区域，这些区域涉及视觉、听觉和空间处理，支持在感知和心理再激活过程中对刺激的特异性表示。在感知过程中，与年龄相关的去分化证据是微妙的，但在心理再激活过程中更为明显，并且感知过程中的年龄差异并不能解释老年人神经再激活特异性降低的原因。视频细节的扫描后识别任务表现与年轻参与者的神经再激活相关，但与年长参与者无关，这表明在扫描过程中的再激活有助于年轻成年人的扫描后识别，但一些年长参与者可能受益于替代的排练策略。尽管年轻参与者在扫描后回忆任务中比年长参与者回忆出更多关于视频刺激的细节，但在两个年龄组中，神经再激活的模式都与扫描后回忆相关。这些结果表明，支持回忆和再认的机制与年轻和年长成年人中准确的神经再激活相关，但年龄会影响这些机制以有效支持记忆的代表性特异性的方式，而这种影响不能简单地归因于感官处理的退化。
