Bultitude Janet H, Downing Paul E, Rafal Robert D
Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK.
Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Gwynedd, LL57 2AS, UK.
F1000Res. 2013 Oct 14;2:215. doi: 10.12688/f1000research.2-215.v1. eCollection 2013.
Patients with hemispatial neglect ('neglect') following a brain lesion show difficulty responding or orienting to objects and events on the left side of space. Substantial evidence supports the use of a sensorimotor training technique called prism adaptation as a treatment for neglect. Reaching for visual targets viewed through prismatic lenses that induce a rightward shift in the visual image results in a leftward recalibration of reaching movements that is accompanied by a reduction of symptoms in patients with neglect. The understanding of prism adaptation has also been advanced through studies of healthy participants, in whom adaptation to leftward prismatic shifts results in temporary neglect-like performance. Interestingly, prism adaptation can also alter aspects of non-lateralised spatial attention. We previously demonstrated that prism adaptation alters the extent to which neglect patients and healthy participants process local features versus global configurations of visual stimuli. Since deficits in non-lateralised spatial attention are thought to contribute to the severity of neglect symptoms, it is possible that the effect of prism adaptation on these deficits contributes to its efficacy. This study examines the pervasiveness of the effects of prism adaptation on perception by examining the effect of prism adaptation on configural face processing using a composite face task. The composite face task is a persuasive demonstration of the automatic global-level processing of faces: the top and bottom halves of two familiar faces form a seemingly new, unknown face when viewed together. Participants identified the top or bottom halves of composite faces before and after prism adaptation. Sensorimotor adaptation was confirmed by significant pointing aftereffect, however there was no significant change in the extent to which the irrelevant face half interfered with processing. The results support the proposal that the therapeutic effects of prism adaptation are limited to dorsal stream processing.
脑部损伤后出现半侧空间忽视（“忽视”）的患者，在对空间左侧的物体和事件做出反应或定向时存在困难。大量证据支持使用一种名为棱镜适应的感觉运动训练技术来治疗忽视。通过棱镜镜片观察视觉目标，该镜片会使视觉图像向右偏移，这会导致伸手动作向左重新校准，同时伴有忽视患者症状的减轻。对棱镜适应的理解也通过对健康参与者的研究得到了推进，在这些参与者中，对向左棱镜偏移的适应会导致暂时的类似忽视的表现。有趣的是，棱镜适应还可以改变非偏侧化空间注意力的某些方面。我们之前证明，棱镜适应会改变忽视患者和健康参与者处理视觉刺激的局部特征与整体构型的程度。由于非偏侧化空间注意力的缺陷被认为会导致忽视症状的严重程度，因此棱镜适应对这些缺陷的影响可能有助于其疗效。本研究通过使用合成面孔任务来检验棱镜适应对构型面孔加工的影响，从而考察棱镜适应对感知影响的普遍性。合成面孔任务有力地证明了面孔在全局层面的自动加工：当一起观看时，两张熟悉面孔的上半部分和下半部分会形成一张看似全新的、不认识的面孔。参与者在棱镜适应前后识别合成面孔的上半部分或下半部分。感觉运动适应通过显著的指向后效得到证实，然而，无关的面孔半部对加工的干扰程度没有显著变化。结果支持了这样的观点，即棱镜适应的治疗效果仅限于背侧通路加工。
