Krembil Neuroscience Centre, University Health Network, Canada.
Neuropsychologia. 2010 Dec;48(14):4142-7. doi: 10.1016/j.neuropsychologia.2010.10.013. Epub 2010 Oct 15.
Parkinson's disease (PD) is associated with episodic memory deficits, but their exact nature is unclear. Some dual-process studies have suggested that recollection is impaired and familiarity is spared in PD, yet others have found the opposite. Our goal was to investigate these memory processes in PD and determine whether the inconsistency among existing findings is related to differences in encoding conditions. We used a process-dissociation procedure with word pairs to estimate familiarity and recollection. In Experiment 1, we used a directed, deep, relational encoding condition (i.e., sentence generation), and in Experiment 2, we contrasted this encoding condition with a shallower, non-directed encoding condition (i.e., read condition). We found a double dissociation as a function of the encoding task: In the sentence generation encoding condition, recollection was impaired in the PD patients, but familiarity was spared. In contrast, in the read encoding condition, there was no group difference in recollection, but familiarity was impaired in the PD group. Within-subject comparisons revealed that both control and PD participants benefitted from the provision of a directed, deep relational encoding strategy. However, this benefit was manifested as an increase in recollection in the controls, but an increase in familiarity in the PD patients. These findings help to reconcile the extant literature and suggest that episodic memory deficits in PD are two-fold, involving: (1) difficulties instantiating encoding strategies independently, leading to deficits in familiarity, and (2) impaired recollection when encoding strategies are equated across groups. Our results highlight the importance of controlling encoding conditions between groups and of taking account of other variables that may influence the participants' performance, such as deficits associated with normal aging, which may mask deficits in neurodegenerative diseases in particular situations. More generally, our study raises the possibility that deficits in recollection or familiarity in patient populations are not immutably linked to the structure that is affected, as is typically assumed, but that such deficits may interact with type of encoding, and possibly with the nature of the retrieval process.
帕金森病（PD）与情景记忆缺陷有关，但确切性质尚不清楚。一些双加工研究表明，PD 患者的再认受损，熟悉度未受损，但也有相反的发现。我们的目标是研究 PD 中的这些记忆过程，并确定现有研究结果之间的不一致是否与编码条件的差异有关。我们使用词对的过程分离程序来估计熟悉度和再认。在实验 1 中，我们使用了定向、深入、关系性的编码条件（即句子生成），在实验 2 中，我们将这种编码条件与较浅、非定向的编码条件（即阅读条件）进行了对比。我们发现了一种双分离，这是一个函数的编码任务：在句子生成编码条件下，PD 患者的再认受损，但熟悉度未受损。相比之下，在阅读编码条件下，PD 患者的再认没有差异，但熟悉度受损。个体内比较显示，控制组和 PD 组患者都受益于提供定向、深入的关系性编码策略。然而，这种好处表现为控制组的再认增加，而 PD 组的熟悉度增加。这些发现有助于调和现有的文献，并表明 PD 中的情景记忆缺陷是双重的，涉及：（1）独立实施编码策略的困难，导致熟悉度下降，以及（2）当编码策略在组间相同时，再认受损。我们的结果强调了在组间控制编码条件的重要性，以及考虑可能影响参与者表现的其他变量的重要性，例如与正常衰老相关的缺陷，这可能会在特定情况下掩盖神经退行性疾病的缺陷。更一般地说，我们的研究提出了这样一种可能性，即患者群体中的再认或熟悉度缺陷与其受影响的结构并不像通常假设的那样不可改变地相关，而是可能与编码类型以及可能与检索过程的性质相互作用。
