Cazzoli Dario, Rosenthal Clive R, Kennard Christopher, Zito Giuseppe A, Hopfner Simone, Müri René M, Nyffeler Thomas
Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom; University Hospital of Old Age Psychiatry, University of Bern, Bern, Switzerland; ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
Cortex. 2015 Dec;73:317-29. doi: 10.1016/j.cortex.2015.09.009. Epub 2015 Oct 20.
Visual neglect is considerably exacerbated by increases in visual attentional load. These detrimental effects of attentional load are hypothesised to be dependent on an interplay between dysfunctional inter-hemispheric inhibitory dynamics and load-related modulation of activity in cortical areas such as the posterior parietal cortex (PPC). Continuous Theta Burst Stimulation (cTBS) over the contralesional PPC reduces neglect severity. It is unknown, however, whether such positive effects also operate in the presence of the detrimental effects of heightened attentional load. Here, we examined the effects of cTBS on neglect severity in overt visual search (i.e., with eye movements), as a function of high and low visual attentional load conditions. Performance was assessed on the basis of target detection rates and eye movements, in a computerised visual search task and in two paper-pencil tasks. cTBS significantly ameliorated target detection performance, independently of attentional load. These ameliorative effects were significantly larger in the high than the low load condition, thereby equating target detection across both conditions. Eye movement analyses revealed that the improvements were mediated by a redeployment of visual fixations to the contralesional visual field. These findings represent a substantive advance, because cTBS led to an unprecedented amelioration of overt search efficiency that was independent of visual attentional load.
视觉注意负荷的增加会显著加剧视觉忽视。据推测，注意负荷的这些有害影响依赖于半球间抑制功能障碍动力学与诸如顶叶后皮质（PPC）等皮质区域活动的负荷相关调制之间的相互作用。对健侧PPC进行连续theta爆发刺激（cTBS）可降低忽视的严重程度。然而，尚不清楚在注意负荷增加的有害影响存在的情况下，这种积极作用是否也能发挥作用。在此，我们研究了cTBS对公开视觉搜索（即伴有眼球运动）中忽视严重程度的影响，该影响是高、低视觉注意负荷条件的函数。在计算机化视觉搜索任务以及两项纸笔任务中，根据目标检测率和眼球运动来评估表现。cTBS显著改善了目标检测表现，且与注意负荷无关。在高负荷条件下，这些改善效果比低负荷条件下显著更大，从而使两种条件下的目标检测达到同等水平。眼球运动分析表明，这些改善是通过将视觉注视重新部署到健侧视野来介导的。这些发现代表了一项实质性进展，因为cTBS导致了公开搜索效率前所未有的改善，且与视觉注意负荷无关。
