MRC Cognition and Brain Sciences Unit, Cambridge, UK.
Cortex. 2011 Mar;47(3):353-66. doi: 10.1016/j.cortex.2010.01.006. Epub 2010 Jan 21.
Previous research has shown that prism adaptation (prism adaptation) can ameliorate several symptoms of spatial neglect after right-hemisphere damage. But the mechanisms behind this remain unclear. Recently we reported that prisms may increase leftward awareness for neglect in a task using chimeric visual objects, despite apparently not affecting awareness in a task using chimeric emotional faces (Sarri et al., 2006). Here we explored potential reasons for this apparent discrepancy in outcome, by testing further whether the lack of a prism effect on the chimeric face task task could be explained by: i) the specific category of stimuli used (faces as opposed to objects); ii) the affective nature of the stimuli; and/or iii) the particular task implemented, with the chimeric face task requiring forced-choice judgements of lateral 'preference' between pairs of identical, but left/right mirror-reversed chimeric face tasks (as opposed to identification for the chimeric object task). We replicated our previous pattern of no impact of prisms on the emotional chimeric face task here in a new series of patients, while also similarly finding no beneficial impact on another lateral 'preference' measure that used non-face non-emotional stimuli, namely greyscale gradients. By contrast, we found the usual beneficial impact of prism adaptation (prism adaptation) on some conventional measures of neglect, and improvements for at least some patients in a different face task, requiring explicit discrimination of the chimeric or non-chimeric nature of face stimuli. The new findings indicate that prism therapy does not alter spatial biases in neglect as revealed by 'lateral preference tasks' that have no right or wrong answer (requiring forced-choice judgements on left/right mirror-reversed stimuli), regardless of whether these employ face or non-face stimuli. But our data also show that prism therapy can beneficially modulate some aspects of visual awareness in spatial neglect not only for objects, but also for face stimuli, in some cases.
先前的研究表明，棱镜适应（prism adaptation）可以改善右半球损伤后空间忽视的几种症状。但是，其背后的机制尚不清楚。最近，我们报告说，尽管棱镜在使用混合视觉物体的任务中似乎不会影响意识，但棱镜可能会增加对忽视的左向意识（Sarri 等人，2006 年）。在这里，我们通过进一步测试棱镜对混合面部任务是否缺乏影响，是否可以解释为：i）使用的刺激物特定类别（物体而不是面部）；ii）刺激物的情感性质；和/或 iii）实施的特定任务，与需要对相同的但左右镜像反转的混合面部任务之间的侧“偏好”进行强制选择判断的混合面部任务（与混合对象任务的识别相反）。我们在一系列新的患者中复制了我们之前的研究结果，即棱镜对情绪混合面部任务没有影响，同时也发现棱镜对另一种侧“偏好”测量没有有益的影响，该测量使用非面部非情感刺激，即灰度梯度。相比之下，我们发现棱镜适应（prism adaptation）对一些常规的忽视测量有通常的有益影响，并且对于至少一些患者在需要明确区分混合或非混合面部刺激的不同面部任务中也有改善。新发现表明，棱镜疗法不会改变由没有正确或错误答案的“侧偏任务”（对左右镜像反转的刺激进行强制选择判断）揭示的忽视空间偏见，无论这些任务使用面部还是非面部刺激。但是，我们的数据还表明，棱镜疗法不仅可以使物体的空间忽视的某些方面，而且还可以使某些情况下的面部刺激的某些方面的视觉意识得到有益的调节。
