Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands.
Maastricht Brain Imaging Centre, Maastricht, the Netherlands.
Neuropsychol Rev. 2024 Sep;34(3):838-849. doi: 10.1007/s11065-023-09614-2. Epub 2023 Sep 22.
Hemispheric asymmetry is a fundamental principle in the functional architecture of the brain. It plays an important role in attention research where right hemisphere dominance is core to many attention theories. Lesion studies seem to confirm such hemispheric dominance with patients being more likely to develop left hemineglect after right hemispheric stroke than vice versa. However, the underlying concept of hemispheric dominance is still not entirely clear. Brain stimulation studies using transcranial magnetic stimulation (TMS) might be able to illuminate this concept. To examine the putative hemispheric asymmetry in spatial attention, we conducted a meta-analysis of studies applying inhibitory TMS protocols to the left or right posterior parietal cortices (PPC), assessing effects on attention biases with the landmark and line bisection task. A total of 18 studies including 222 participants from 1994 to February 2022 were identified. The analysis revealed a significant shift of the perceived midpoint towards the ipsilateral hemifield after right PPC suppression (Cohen's d = 0.52), but no significant effect after left PPC suppression (Cohen's d = 0.26), suggesting a hemispheric asymmetry even though the subgroup difference does not reach significance (p = .06). A complementary Bayesian meta-analysis revealed a high probability of at least a medium effect size after right PPC disruption versus a low probability after left PPC disruption. This is the first quantitative meta-analysis supporting right hemisphere-specific TMS-induced spatial attention deficits, mimicking hemineglect in healthy participants. We discuss the result in the light of prominent attention theories, ultimately concluding how difficult it remains to differentiate between these theories based on attentional bias scores alone.
大脑功能结构的一个基本原则是大脑的半球不对称性。它在注意力研究中起着重要作用，其中右半球优势是许多注意力理论的核心。病变研究似乎证实了这种半球优势，患者在右半球中风后更有可能出现左侧忽略，而不是相反。然而，半球优势的基本概念仍不完全清楚。使用经颅磁刺激（TMS）的脑刺激研究可能能够阐明这一概念。为了研究空间注意力的潜在半球不对称性，我们对应用抑制性 TMS 方案到左或右顶后皮质（PPC）的研究进行了荟萃分析，评估地标和线二分任务对注意力偏向的影响。从 1994 年到 2022 年 2 月，共确定了 18 项研究，包括 222 名参与者。分析显示，右 PPC 抑制后，感知中点明显偏向同侧视野（Cohen's d=0.52），而左 PPC 抑制后无明显影响（Cohen's d=0.26），表明存在半球不对称性，尽管亚组差异没有达到显著性（p=0.06）。补充的贝叶斯荟萃分析显示，右 PPC 破坏后至少有中等效应量的可能性很高，而左 PPC 破坏后则可能性较低。这是第一个支持右半球特定 TMS 诱导的空间注意力缺陷的定量荟萃分析，在健康参与者中模拟了半忽视。我们根据突出的注意力理论讨论了结果，最终得出结论，仅根据注意力偏向得分很难区分这些理论。
