Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TP, UK.
Neuropsychologia. 2010 Mar;48(4):887-99. doi: 10.1016/j.neuropsychologia.2009.11.006. Epub 2009 Nov 11.
Individuals with Parkinson's disease (PD) show marked impairments in their ability to generate self-initiated, or "voluntary", saccadic eye movements. Investigations of visually guided, or "reflexive", saccades have, on the other hand, produced inconclusive results with studies showing response times (RTs) in persons with PD that are slower, faster, or indistinguishable from those of controls. We performed a meta-analysis to establish whether there are consistent effects of PD on the metrics of visually guided saccades. Combining results across 47 studies we found that reflexive saccades are overall initiated more slowly in persons with PD than in controls, however, this analysis also revealed considerable heterogeneity across studies. Step-wise meta-regression, using eleven potential predictors, subsequently showed that differences in mean RT between controls and persons with PD may arise due to aspects of experimental design. In particular, mean target eccentricity was shown to impact substantially on RTs such that persons with PD predictably initiate saccades faster than controls at small target eccentricities, while responding more slowly for large target eccentricities. Changes in eye-tracking and display equipment over the period covered by the review were also found to have impacted on the pattern of results obtained. We conclude that a, previously unsuspected, eccentricity effect could explain why the saccadic eye movements of persons with PD are sometimes found to be "hyper-reflexive" compared to controls, and suggest that this effect may arise due to PD-induced changes in both peripheral perceptual processing and in central executive mechanisms involving the basal ganglia.
帕金森病（PD）患者在自主产生，即“自愿”眼跳的能力上存在明显障碍。另一方面，对视觉引导的，即“反射性”眼跳的研究结果却不一致，一些研究表明 PD 患者的反应时间（RT）较慢、较快或与对照组无区别。我们进行了一项荟萃分析，以确定 PD 是否对视觉引导的眼跳的度量有一致的影响。综合 47 项研究的结果，我们发现 PD 患者的反射性眼跳总体上比对照组更慢，但该分析也显示出研究之间存在相当大的异质性。随后，使用十一个潜在预测因子逐步进行荟萃回归分析表明，PD 患者与对照组之间的平均 RT 差异可能源于实验设计的各个方面。特别是，平均目标偏心率显示出对 RT 有重大影响，使得 PD 患者在小目标偏心率时比对照组更可预测地更快地发起眼跳，而在大目标偏心率时反应较慢。回顾期间眼动追踪和显示设备的变化也被发现对所获得结果的模式产生了影响。我们的结论是，以前未被怀疑的偏心率效应可以解释为什么与对照组相比，PD 患者的扫视眼动有时被认为是“超反射性”的，并表明这种效应可能是由于 PD 引起的外周感知处理和涉及基底神经节的中央执行机制的变化所致。
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