Roberts Daniel J, Lambon Ralph Matthew A, Kim Esther, Tainturier Marie-Josephe, Beeson Pelagie M, Rapcsak Steven Z, Woollams Anna M
Research Centre in Brain and Behaviour, Liverpool John Moores University, UK.
Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester, UK.
Cortex. 2015 Nov;72:79-96. doi: 10.1016/j.cortex.2015.02.003. Epub 2015 Feb 26.
Pure alexia (PA) arises from damage to the left posterior fusiform gyrus (pFG) and the striking reading disorder that defines this condition has meant that such patients are often cited as evidence for the specialisation of this region to processing of written words. There is, however, an alternative view that suggests this region is devoted to processing of high acuity foveal input, which is particularly salient for complex visual stimuli like letter strings. Previous reports have highlighted disrupted processing of non-linguistic visual stimuli after damage to the left pFG, both for familiar and unfamiliar objects and also for novel faces. This study explored the nature of face processing deficits in patients with left pFG damage. Identification of famous faces was found to be compromised in both expressive and receptive tasks. Discrimination of novel faces was also impaired, particularly for those that varied in terms of second-order spacing information, and this deficit was most apparent for the patients with the more severe reading deficits. Interestingly, discrimination of faces that varied in terms of feature identity was considerably better in these patients and it was performance in this condition that was related to the size of the length effects shown in reading. This finding complements functional imaging studies showing left pFG activation for faces varying only in spacing and frontal activation for faces varying only on features. These results suggest that the sequential part-based processing strategy that promotes the length effect in the reading of these patients also allows them to discriminate between faces on the basis of feature identity, but processing of second-order configural information is most compromised due to their left pFG lesion. This study supports a view in which the left pFG is specialised for processing of high acuity foveal visual information that supports processing of both words and faces.
纯失读症（PA）源于左侧梭状回后部（pFG）受损，而定义这种病症的显著阅读障碍意味着此类患者常被引为该区域专门处理书面文字的证据。然而，另一种观点认为该区域专门处理高敏锐度的中央凹输入信息，这对于像字母串这样的复杂视觉刺激尤为显著。先前的报告强调，左侧pFG受损后，非语言视觉刺激的处理会受到干扰，无论是熟悉还是不熟悉的物体，以及新面孔。本研究探讨了左侧pFG受损患者面部处理缺陷的本质。研究发现，在表达性和接受性任务中，名人面孔的识别均受到损害。新面孔的辨别也受到损害，特别是对于那些在二阶间距信息方面存在差异的面孔，而这种缺陷在阅读缺陷更严重的患者中最为明显。有趣的是，这些患者对面孔特征差异的辨别能力要好得多，而且正是在这种情况下的表现与阅读中显示的长度效应大小相关。这一发现补充了功能成像研究的结果，即左侧pFG对面孔仅在间距上的变化有激活，而额叶对面孔仅在特征上的变化有激活。这些结果表明，促进这些患者阅读中长度效应的基于部分的顺序处理策略，也使他们能够根据特征识别来辨别面孔，但由于左侧pFG病变，二阶构型信息的处理受到的损害最大。本研究支持这样一种观点，即左侧pFG专门用于处理高敏锐度的中央凹视觉信息，该信息支持单词和面孔的处理。
