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Foveal vision is delivered to the pFG and this region is maximally active for categories of visual stimuli that require fine visual discrimination/foveation (faces and words Hasson et al. Visual acuity (sensitivity to high spatial frequencies) is highest in the fovea and drops toward the parafoveal region ( Fiset et al. (2002) proposed that this graded functional separation reflects the visual demands of each type of stimuli and, in turn, the acuity variation across retinal eccentricity. Within this region, specific areas respond maximally to different object categories (animals, objects, houses, faces, and words). 2002) which runs from the pFG to the collateral sulcus. 2002) have proposed the notion of a retinotopically organized ventral occipito-temporal area (vOT Malach et al. On the basis of functional imaging studies in normal subjects, Malach and colleagues ( Levy et al. More specifically, we explored the visual processing of patients with vOT damage in the context of potentially important insights offered by recent visual neuroscience studies of this region. The primary purpose of this study was not to add to this ongoing, vibrant debate between the competing cognitive theories ( Dehaene and Cohen 2011 Price and Devlin 2011) but was to initiate an investigation about why the left pFG region appears to be crucial for the recognition of visually complex orthographic and non-orthographic stimuli. 1998a, b Price and Devlin 2003, 2011 Devlin et al. 2001, 2004, 2005 Dehaene and Cohen 2011) or because this region is crucial in some way for rapid decoding of complex visual stimuli-a process that reading is especially reliant upon ( Price et al.

Cognitive theories, combining neuropsychological and functional neuroimaging data, have suggested that the left pFG is important for orthographic recognition either because this area has become specialized for this specific stimulus type ( Cohen et al. Lesion-deficit correlation studies have provided evidence that the critical neural substrate of pure alexia is damage to the posterior fusiform gyrus (pFG Damasio and Damasio 1983 Binder and Mohr 1992 Cohen et al. This contrasts with normal word reading, where length exerts little influence on performance ( Weekes 1997). In alphabetic languages, the hallmark symptom of pure alexia is slowed, inefficient processing of letter strings with an exaggerated effect of word length on reading performance ( Shallice and Saffran 1986 Roberts et al. 1997), or visual semantic access disorders ( Warrington and Shallice 1979, 1980). This pattern is known as pure alexia or letter-by-letter reading ( Dejerine 1892), while more severe patients also suffer from visual agnosia, optic aphasia ( Humphreys et al. A classic presentation of patients with left vOT damage is a reading deficit without significant spelling or spoken language impairment other than anomia ( Benson and Geschwind 1969 Capitani et al. Lesions involving ventral occipito-temporal cortex (vOT) typically arise from cerebral ischemia in the territory of the posterior cerebral artery, head trauma, or surgical ablation. These results suggest that the patients' dual reading and non-orthographic recognition impairments have a common underlying mechanism and reflect the loss of high spatial frequency visual information normally coded in the left pFG.

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Consistent with this hypothesis, we obtained evidence that a large case series ( n = 20) of patients with lesions centered on left pFG: 1) Exhibited reduced sensitivity to high spatial frequencies 2) demonstrated prolonged response latencies both in reading (pure alexia) and object naming and 3) were especially sensitive to visual complexity and similarity when discriminating between novel visual patterns. Because high spatial frequencies are critical for fine-grained visual discrimination, we hypothesized that damage to the left pFG should have an adverse effect not only on efficient reading, as observed in pure alexia, but also on the processing of complex non-orthographic visual stimuli. Recent visual neuroscience investigations suggest that ventral occipito-temporal cortex is retinotopically organized, with high acuity foveal input projecting primarily to the posterior fusiform gyrus (pFG), making this region crucial for coding high spatial frequency information.