Giglhuber Katrin, Maurer Stefanie, Zimmer Claus, Meyer Bernhard, Krieg Sandro M
Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany.
TUM-Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
BMC Neurosci. 2018 Jul 11;19(1):40. doi: 10.1186/s12868-018-0440-1.
Visuospatial attention is executed by the frontoparietal cortical areas of the brain. Damage to these areas can result in visual neglect. We therefore aimed to assess a combination of the greyscales task and repetitive navigated transcranial magnetic stimulation (rTMS) to identify cortical regions involved in visuospatial attention processes. This pilot study was designed to evaluate an approach in a cohort of healthy volunteers, with the future aim of using this technique to map brain tumor patients before surgery. Ten healthy, right-handed subjects underwent rTMS mapping of 52 cortical spots in both hemispheres. The greyscales task was presented tachistoscopically and was time-locked to rTMS pulses. The task pictures showed pairs of horizontal rectangles shaded continuously from black at one end to white at the other, mirror-reversed. On each picture the subject was asked to report which of the two greyscales appeared darker overall. The responses were categorized into "leftward" and "rightward," depending on whether the subject had chosen the rectangle with the darker end on the left or the right. rTMS applied to cortical areas involved in visuospatial attention is supposed to affect lateral shifts in spatial bias. These shifts result in an altered performance on the greyscales task compared to the baseline performance without rTMS stimulation.
In baseline conditions, 9/10 subjects showed classic pseudoneglect to the left. Leftward effects also occurred more often in mapping conditions. Yet, calculated rightward deviations were strikingly greater in magnitude (p < 0.0001). Overall, the right hemisphere was found to be more suggestible than the left hemisphere. Both rightward and leftward deviation scores were higher for the rTMS of this brain side (p < 0.0001). Right hemispheric distributions accord well with current models of visuospatial attention (Corbetta et al. Nat Neurosci 8(11):1603-1610, 2005). We observed leftward deviations triggered by rTMS within superior frontal and posterior parietal areas and rightward deviations within inferior frontal areas and the temporoparietal junction (TPJ).
The greyscales task, in combination with rTMS, yields encouraging results in the examination of the visuospatial attention function. Future clinical implications should be evaluated.
视觉空间注意力由大脑的额顶叶皮质区域执行。这些区域受损会导致视觉忽视。因此，我们旨在评估灰度任务和重复导航经颅磁刺激（rTMS）的组合，以确定参与视觉空间注意力过程的皮质区域。这项初步研究旨在评估一组健康志愿者的方法，未来的目标是使用该技术在术前对脑肿瘤患者进行脑图谱绘制。10名健康的右利手受试者接受了双侧52个皮质点的rTMS图谱绘制。灰度任务通过速示器呈现，并与rTMS脉冲同步。任务图片显示成对的水平矩形，从一端的黑色到另一端的白色连续渐变，呈镜像反转。在每张图片上，要求受试者报告两个灰度中哪个总体上看起来更暗。根据受试者选择的是左端较暗还是右端较暗的矩形，将反应分为“向左”和“向右”。应用于参与视觉空间注意力的皮质区域的rTMS应该会影响空间偏差的横向偏移。与没有rTMS刺激的基线表现相比，这些偏移会导致灰度任务的表现发生改变。
在基线条件下，9/10的受试者表现出对左侧的典型假性忽视。在图谱绘制条件下，向左的效应也更常出现。然而，计算出的向右偏差在幅度上明显更大（p < 0.0001）。总体而言，发现右半球比左半球更易受影响。该脑侧的rTMS的向右和向左偏差分数均更高（p < 0.0001）。右半球的分布与当前的视觉空间注意力模型（Corbetta等人，《自然神经科学》8(11):1603 - 1610，2005）非常吻合。我们观察到rTMS在额上回和顶叶后部区域引发向左偏差，在额下回和颞顶联合区（TPJ）引发向右偏差。
灰度任务与rTMS相结合，在视觉空间注意力功能检查中产生了令人鼓舞的结果。未来的临床意义应予以评估。
