Robertson I H, Mattingley J B, Rorden C, Driver J
MRC Cognition and Brain Sciences Unit, Cambridge, UK.
Nature. 1998 Sep 10;395(6698):169-72. doi: 10.1038/25993.
Patients with extensive damage to the right hemisphere of their brain often exhibit unilateral neglect of the left side of space. The spatial attention of these patients is strongly biased towards the right, so their awareness of visual events on the left is impaired. Extensive right-hemisphere lesions also impair tonic alertness (the ability to maintain arousal). This nonspatial deficit in alertness is often considered to be a different problem from spatial neglect, but the two impairments may be linked. If so, then phasically increasing the patients' alertness should temporarily ameliorate their spatial bias in awareness. Here we provide evidence to support this theory. Right-hemisphere-neglect patients judged whether a visual event on the left preceded or followed a comparable event on the right. They became aware of left events half a second later than right events on average. This spatial imbalance in the time course of visual awareness was corrected when a warning sound alerted the patients phasically. Even a warning sound on the right accelerated the perception of left visual events in this way. Nonspatial phasic alerting can thus overcome disabling spatial biases in perceptual awareness after brain injury.
大脑右半球受到广泛损伤的患者常常表现出对左侧空间的单侧忽视。这些患者的空间注意力强烈偏向右侧，因此他们对左侧视觉事件的感知能力受损。广泛的右半球损伤还会损害紧张性警觉（维持觉醒的能力）。这种警觉方面的非空间缺陷通常被认为与空间忽视是不同的问题，但这两种损伤可能存在关联。如果是这样，那么阶段性地提高患者的警觉性应该会暂时改善他们在感知上的空间偏向。在此我们提供证据来支持这一理论。右半球忽视患者要判断左侧的视觉事件是先于还是后于右侧的类似事件出现。他们意识到左侧事件的时间平均比右侧事件晚半秒。当一个警示音阶段性地提醒患者时，视觉感知时间进程中的这种空间不平衡就得到了纠正。即使是右侧的警示音也能以这种方式加速对左侧视觉事件的感知。因此，非空间性的阶段性警觉能够克服脑损伤后感知觉中导致障碍的空间偏向。
