Mattingley Jason B, Berberovic Nadja, Corben Louise, Slavin Melissa J, Nicholls Michael E R, Bradshaw John L
Cognitive Neuroscience Laboratory, Department of Psychology, University of Melbourne, Melbourne, Vic. 3010, Australia.
Neuropsychologia. 2004;42(3):387-94. doi: 10.1016/j.neuropsychologia.2003.07.007.
The two cerebral hemispheres in humans have been suggested to control contralaterally opposed attentional biases. These biases may be revealed by unilateral hemispheric damage, which often causes contralesional spatial neglect, particularly when the right hemisphere (RH) is affected. Subtle attentional biases have also been observed in normal observers in tasks requiring judgements of horizontal spatial extent, brightness, numerosity and size. Here, we examined attentional biases for judging the darker of two left-right mirror-reversed brightness gradients under conditions of free viewing (the greyscales task). We compared performances of patients with damage to the RH (n=78) and left hemisphere (LH; n=20) with those of normal controls (n=20). Controls showed a small but significant leftward bias, implying a subtle asymmetry favouring the RH. In contrast, RH and LH patients showed extreme rightward and leftward biases, respectively, both of which differed significantly from that of controls. For the patient groups, performance on clinical tests of neglect (cancellation and line bisection) did not predict their greyscales scores. Pathological biases were present in patients without clinical neglect or visual field defects, suggesting that the attentional bias measured by the greyscales task can be dissociated from clinical neglect and visual sensory loss. The greyscales task offers an efficient means of quantifying pathological attentional biases in unilateral lesion patients; it is easy to administer and score, and may be particularly useful for clinical trials of recovery and rehabilitation following stroke.
有人提出，人类的两个大脑半球控制着对侧相反的注意偏向。这些偏向可能通过单侧半球损伤表现出来，这种损伤常导致对侧空间忽视，尤其是当右侧半球（RH）受到影响时。在要求对水平空间范围、亮度、数量和大小进行判断的任务中，正常观察者也观察到了细微的注意偏向。在这里，我们研究了在自由观看条件下（灰度任务）判断左右镜像反转的两个亮度梯度中较暗者时的注意偏向。我们比较了右侧半球（n = 78）和左侧半球（LH；n = 20）损伤患者与正常对照组（n = 20）的表现。对照组表现出轻微但显著的向左偏向，这意味着存在有利于右侧半球的细微不对称性。相比之下，右侧半球和左侧半球损伤患者分别表现出极端的向右和向左偏向，两者均与对照组有显著差异。对于患者组，忽视的临床测试（删除和直线二等分）成绩并不能预测他们的灰度得分。在没有临床忽视或视野缺损的患者中也存在病理性偏向，这表明灰度任务所测量的注意偏向可能与临床忽视和视觉感觉丧失无关。灰度任务为量化单侧病变患者的病理性注意偏向提供了一种有效的方法；它易于实施和评分，可能对中风后恢复和康复的临床试验特别有用。
