Specialization within the ventral stream: the case for the visual word form area

Available evidence from single-subject fMRI and intracranial recordings suggests that some cortical sites respond preferentially to letter strings than to other categories of visual stimuli such as faces or objects, though the preference is often relative rather than absolute.

“The available evidence from single-subject fMRI and intracranial recordings suggests that some cortical sites respond preferentially to letter strings than to other categories of visual stimuli such as faces or objects, though the preference is often relative rather than absolute.”

Patients with pure alexia consistently exhibit lesions of this region.

“patients with pure alexia consistently exhibit lesions of this region (reproducible localization).”

Reading activates a precise subpart of the left ventral occipitotemporal sulcus.

“Examination of the literature with this theoretical division in mind indicates that reading activates a precise subpart of the left ventral occipitotemporal sulcus”

There is not complete regional selectivity for word recognition.

“We do not, however, believe that there is complete regional selectivity for word recognition.”

A large number of studies, using various methods, have evidenced a reproducible activation of the left fusiform gyrus during reading.

“A large number of studies, using various methods, have evidenced a reproducible activation of the left fusiform gyrus during reading.”

• cites Beauregard et al., 1997 sourceNot checked yet

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• cites Brunswick et al., 1999 sourceNot checked yet

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• cites Dehaene et al., 2002 sourceNot checked yet

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Evidence from priming or adaptation paradigms provides evidence for functional specialization for case-invariant letter recognition in the left fusiform region.

“although it provides evidence for functional specialization for case-invariant letter recognition in the left fusiform region (Dehaene et al., 2001; Dehaene et al., in press).”

• cites Dehaene et al., 2001 sourceNot checked yet

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• cites Dehaene et al., in pressNot checked yet

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Activation in the left fusiform gyrus during reading can be identified merely by contrasting word reading relative to rest, either with PET or with fMRI.

“Activation in this region can be identified merely by contrasting word reading relative to rest, either with PET or with fMRI (Beauregard et al., 1997; Brunswick et al., 1999; Dehaene et al., 2002; Fiez et al., 1999; Paulesu et al., 2000; Wagner et al., 1998).”

• cites Beauregard et al., 1997 sourceNot checked yet

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• cites Brunswick et al., 1999 sourceNot checked yet

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• cites Dehaene et al., 2002 sourceNot checked yet

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The left fusiform region appears as a likely source of electrical and magnetic fields that are recorded over the left ventral occipitotemporal region, with a latency of about 150-200 ms, whenever subjects see words.

“This region appears as a likely source of electrical and magnetic fields that are recorded over the left ventral occipitotemporal region, with a latency of about 150-200 ms, whenever subjects see words (Allison et al., 1994, 1999; Cohen et al., 2000; Nobre et al., 1994; Salmelin et al., 1996; Simos et al., 2002; Tarkiainen et al., 1999).”

• cites Allison et al., 1994, 1999Not matched

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• cites Cohen et al., 2000 sourceNot checked yet

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• cites Nobre et al., 1994 sourceNot checked yet

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Even the voxels that respond optimally to words tend to be also activated by other stimuli such as pictures or line drawings of objects.

“Even the voxels that respond optimally to words tend to be also activated by other stimuli such as pictures or line drawings of objects.”

The VWFA is found at the same location in Talairach space (approximately -43, -54, -12) with a standard deviation of only about half a centimeter.

“The VWFA is found at the same location in Talairach space (approximately 43, 54, 12) with a standard deviation of only about half a centimeter.”

The VWFA is tuned to the shape of letters, relative to visually equivalent pseudo-letters.

“First, there are indications that the VWFA is tuned to the shape of letters, relative to visually equivalent pseudo-letters.”

• cites Petersen et al. (1990) sourceNot checked yet

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• cites Price et al. (1996) sourceNot checked yet

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Interindividual variability of the VWFA location is remarkably low.

“This allows quantification of the interindividual variability, which is remarkably low.”

Words in modalities other than the visual yielded activations more anterior (average y = -43) than those typical of the visual word form (average y = -60).

“As already noted by Bu ¨chel et al. (1998), words in modalities other than the visual yielded activations more anterior (average y = 43) than those typical of the visual word form (average y = 60).”

• cites Büchel et al. (1998) sourceNot checked yet

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There is good convergence to the same approximate Talairach coordinates across studies of the VWFA.

“There is good convergence to the same approximate Talairach coordinates across those studies (Cohen et al., 2000).”

• cites Cohen et al., 2000 sourceNot checked yet

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This systematic topographical organization was reproduced by Gauthier et al. (2000).

“This systematic topographical organization was reproduced by Gauthier et al. (2000).”

• cites Gauthier et al. (2000) sourceNot checked yet

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The left occipitotemporal sulcus (average coordinates -44, -68, -4) was activated only by visual words, not by spoken words.

“The left occipitotemporal sulcus (average coordinates 44, 68, 4) was activated only by visual words, not by spoken words.”

Such a distinction is supported by several neuroimaging studies and by intracranial recordings.

“Such a distinction is supported by several neuroimaging studies (e.g. Booth et al., 2002b; see review in Giraud and Price, 2001) as well as by intracranial recordings (Nobre et al., 1994, 1998).”

• cites Booth et al., 2002bNot matched

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• cites Giraud and Price, 2001Not matched

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• cites Nobre et al., 1994, 1998Not matched

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The VWFA can be identified in single subjects.

“Several fMRI papers have further shown that this area can be identified in single subjects (Cohen et al., 2000, 2002; Dehaene et al., 2002; Gauthier et al., 2000; Puce et al., 1996).”

• cites Cohen et al., 2000, 2002Not matched

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• cites Dehaene et al., 2002 sourceNot checked yet

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• cites Gauthier et al., 2000 sourceNot checked yet

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Price et al. (1996) obtained stronger activations to strings of consonants than to strings of pseudo-letters at coordinates close to the VWFA.

“For instance, Price et al. (1996) have obtained stronger activations to strings of consonants than to strings of pseudo-letters at coordinates close to the VWFA.”

• cites Price et al. (1996) sourceNot checked yet

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The VWFA is activated by words presented in either the left or the right hemifield, contrary to more posterior retinotopic areas.

“In one study, we isolated the VWFA using a spatial invariance criterion: contrary to more posterior retinotopic areas, the VWFA is activated by words presented in either the left or the right hemifield (Cohen et al., 2000).”

• cites Cohen et al., 2000 sourceNot checked yet

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Another more lateral and slightly more anterior inferotemporal region (-48, -60, -16) was activated also by spoken words, with modulation by the graphemic task.

“Another more lateral and slightly more anterior inferotemporal region ( 48, 60, 16) was activated also by spoken words, with modulation by the graphemic task.”

Hasson et al. (2002) found a site with greater responsivity to words than to either faces or buildings in the left occipitotemporal sulcus, lateral to face- and building-related activations.

“Hasson et al. (2002) also used fMRI to contrast activations to words, houses, and faces. Again, a site with greater responsivity to words than to either faces or buildings was found in the left occipitotemporal sulcus, lateral to face- and building-related activations.”

• cites Hasson et al. (2002) sourceNot checked yet

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The VWFA responds more to strings of letters than to chequerboards presented in either hemifield.

“In another, we further required this region to respond more to strings of letters than to chequerboards presented in either hemifield (Cohen et al., 2002).”

• cites Cohen et al., 2002 sourceNot checked yet

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In a group analysis, this activation overlapped with the VWFA, as defined by a left inferior temporal activation that was greater to visual than to spoken words.

“In a group analysis, this activation overlapped with the VWFA, as defined by a left inferior temporal activation that was greater to visual than to spoken words.”

In single subjects, the two regions appeared as distinct but very close.

“However, in single subjects, the two regions appeared as distinct but very close.”

The available evidence reveals systematic and reproducible activations that are greater to visual words than to other control stimuli.

“Nevertheless, the available evidence reveals systematic and reproducible activations that are greater to visual words than to other control stimuli.”

Price et al. (1996) observed stronger activation in the left fusiform gyrus to strings of consonants than to strings of false-font characters.

“Following up on the initial insight of Petersen et al. (1990), Price et al. (1996) observed stronger activation in the left fusiform gyrus to strings of consonants than to strings of false-font characters.”

• cites Price et al. (1996) sourceNot checked yet

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Similar results have been obtained using single-subject MEG and intracranial recordings.

“Similar results have been obtained using singlesubjects MEG (Tarkiainen et al., 1999) and intracranial recordings (Allison et al., 1999).”

• cites Tarkiainen et al., 1999 sourceNot checked yet

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• cites Allison et al., 1999 sourceNot checked yet

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Strings of letters cause greater left fusiform activation than visually equivalent strings of digits.

“There is also evidence that strings of letters cause greater left fusiform activation than visually equivalent strings of digits (Polk et al., 2002).”

• cites Polk et al., 2002Not checked yet

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The interference of orthography prevents the detection of the phoneme ''p'' in the spoken French word ''absurde''.

“For instance, the interference of orthography prevents the detection of the phoneme ''p'' in the spoken French word ''absurde'' (Halle ´ et al., 2000).”

• cites Hallé et al., 2000 sourceNot checked yet

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The posterior subpart of mid-fusiform cortex, observed bilaterally, is not invariant for location: it shows priming when single letters are repeated at the same retinal location, irrespective of whether the prime word is identical to the target or an anagram of it.

“The posterior subpart, observed bilaterally, was not invariant for location: it showed priming when single letters were repeated at the same retinal location, irrespective of whether the prime word was identical to the target or was an anagram of it.”

In such cases, reduced activations of the VWFA for words presented in the left hemifield were observed.

“In such cases, we observed reduced activations of the VWFA for words presented in the left hemifield (Cohen et al., 2000; Molko et al., 2002).”

• cites Cohen et al., 2000 sourceNot checked yet

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• cites Molko et al., 2002 sourceNot checked yet

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In a recent word priming study, the mid-fusiform cortex can be decomposed into smaller subareas.

“In a recent word priming study, we found indications that the mid-fusiform cortex can be decomposed into smaller subareas (Dehaene et al., in press).”

• cites Dehaene et al., in pressNot checked yet

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The VWFA shows equally robust fMRI responses when words are presented in a familiar format or in a mixed-case format (e.g. ''tAbLe'').

“The VWFA shows equally robust fMRI responses when words are presented in a familiar format or in a mixed-case format (e.g. ''tAbLe'') (Polk and Farah, 2002).”

• cites Polk and Farah, 2002Not checked yet

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Intracranial recording suggests that there may be specialized subregions for letters vs. digits in the ventral occipitotemporal cortex.

“Indeed, intracranial recording suggests that there may be specialized subregions for letters vs. digits in the ventral occipitotemporal cortex (Allison et al., 1994).”

• cites Allison et al., 1994 sourceNot checked yet

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Such case-invariant priming in the VWFA was recently replicated with words made only of visually dissimilar letters that are related only by arbitrary cultural convention (e.g. a and A, g and G).

“Such case-invariant priming in the VWFA was recently replicated with words made only of visually dissimilar letters that are related only by arbitrary cultural convention (e.g. a and A, g and G) (Dehaene et al., in press).”

• cites Dehaene et al., in pressNot checked yet

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Even more anteriorly in the middle fusiform gyrus, there was a trend towards greater priming when the same word was presented twice compared to when it was preceded by an anagram.

“Finally, even more anteriorily in the middle fusiform gyrus, there was a trend towards greater priming when the same word was presented twice compared to when it was preceded by an anagram, suggesting the presence of the units larger than the letter level.”

In the authors' recent work, a similar region of lesion overlap in the fusiform gyrus was found.

“In our recent work, we also found a similar region of lesion overlap in the fusiform gyrus.”

• cites Cohen et al., 2003 sourceNot checked yet

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The VWFA shows repetition priming whenever a target word is preceded by a subliminal presentation of the same word, whether the two words are printed in the same or in a different case.

“Furthermore, the VWFA shows repetition priming whenever a target word is preceded by a subliminal presentation of the same word, whether the two words are printed in the same or in a different case (e.g. table followed by TABLE) (Dehaene et al., 2001).”

• cites Dehaene et al., 2001 sourceNot checked yet

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The VWFA responds more to words or to pseudo-words than to random consonant strings that violate orthographic constraints.

“Second, the VWFA responds more to words or to pseudo-words than to random consonant strings that violate orthographic constraints (Beauregard et al., 1997; Bu ¨chel et al., 1998; Cohen et al., 2002; Price et al., 1996; Rees et al., 1999; Xu et al., 2001).”

• cites Beauregard et al., 1997 sourceNot checked yet

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• cites Büchel et al., 1998 sourceNot checked yet

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• cites Cohen et al., 2002 sourceNot checked yet

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Most cortical patches that respond to words also activate to other stimuli such as pictures or drawings.

“Nevertheless, most cortical patches that respond to words also activate to other stimuli such as pictures or drawings.”

We are able to recognize words across considerable changes in font, case, location, and size.

“We are able to recognize words across considerable changes in font , CASE, location , and size.”

• cites Besner, 1989 sourceNot checked yet

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• cites Mayall et al., 1997 sourceNot checked yet

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• cites Paap et al., 1984 sourceNot checked yet

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Lesion of this region results in the selective loss of reading-specific processes.

“its lesion results in the selective loss of reading-specific processes (functional specialization).”

The visual word recognition process is highly efficient in normalizing and computing an invariant representation that discards irrelevant variations in the visual input.

“This implies that the visual word recognition process is highly efficient in ''normalizing'' and computing an invariant representation that discards irrelevant variations in the visual input.”

Such perceptual expertise is likely to require specialized neural systems within the ventral visual stream.

“We argue that such perceptual expertise is likely to require specialized neural systems within the ventral visual stream.”

The issue of regional selectivity cannot be resolved by positron emission tomography or lesion data, but requires high-resolution neuroimaging techniques.

“the issue of regional selectivity, namely, the existence of putative cortical patches dedicated to letter and word recognition, cannot be resolved by positron emission tomography or lesion data, but requires high-resolution neuroimaging techniques.”

This region implements processes adequate for reading in a specific script, such as invariance across upper- and lower-case letters.

“this region implements processes adequate for reading in a specific script, such as invariance across upperand lower-case letters”

Learning to read results in the progressive development of an inferotemporal region increasingly responsive to visual words, which is aptly named the visual word form area (VWFA).

“We conclude that learning to read results in the progressive development of an inferotemporal region increasingly responsive to visual words, which is aptly named the visual word form area (VWFA).”

This perceptual expertise requires no less than 5 years of academic training in a specific writing system.

“This perceptual expertise requires no less than 5 years of academic training in a specific writing system (Aghababian and Nazir, 2000).”

• cites Aghababian and Nazir, 2000Not checked yet

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• AssumptionRests on an assumption: Reading in literate adults requires quick identification of visual words across large variations of irrelevant parameters such as position, size, color, font, or case.

At the scale accessible to human neuroimaging, most if not all of the cortical surface is likely to respond jointly to words, faces, and objects, with smooth but systematic changes in local selectivity.

“Therefore, at the scale accessible to human neuroimaging, most if not all of the cortical surface is likely to respond jointly to words, faces, and objects, with smooth but systematic changes in local selectivity (Haxby et al., 2001).”

• cites Haxby et al., 2001 sourceNot checked yet

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There is reproducible localization of the neural circuits that are attuned to the reading process.

“We also propose that there is reproducible localization of the neural circuits that are attuned to the reading process.”

The word superiority effect implies the existence of a mechanism tuned to the possible structures of visual words.

“This phenomenon, which is found with real words, pseudo-words (Spoehr and Smith, 1975), and even nonwords sufficiently similar to words such as SPCT (Rumelhart and McClelland, 1982), implies the existence of a mechanism tuned to the possible structures of visual words.”

The case invariance observed in several psychological experiments must arise from specialization resulting from a learning process.

“Rather, the case invariance observed in several psychological experiments (e.g. Besner et al., 1984; Bowers et al., 1998) must arise from specialization resulting from a learning process.”

• cites Besner et al., 1984 sourceNot checked yet

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• cites Bowers et al., 1998 sourceNot checked yet

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The rather large occipitotemporal region termed VWFA can be further subdivided into, for instance, a posterior location-specific sector and a more anterior location-invariant sector.

“Finally, it is likely that the rather large occipitotemporal region that we have termed VWFA can be further subdivided into, for instance, a posterior location-specific sector and a more anterior location-invariant sector (see Dehaene et al., in press).”

• cites Dehaene et al., in pressNot checked yet

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The absence of a word length effect suggests the presence of a parallel apprehension mechanism specialized for reading.

“This suggests the presence of a parallel apprehension mechanism specialized for reading.”

The finding of overlap between word-related and non-word-related tasks is not conclusive, as it seems likely that even cortical territories known to be distinct would be found to overlap with this method.

“In this context, the finding of overlap between wordrelated and non-word-related (e.g. color or object processing) tasks is not conclusive, as it seems likely that even cortical territories known to be distinct would be found to overlap with this method.”

• AssumptionRests on an assumption: PET group data are typically generated with a spatial smoothness of 15 mm.

Within a range of about three to six letters, visual word recognition takes a constant time regardless of the number of letters composing that word.

“Also remarkable is the absence of any effect of word length: within a range of about three to six letters, visual word recognition takes a constant time regardless of the number of letters composing that word (Lavidor and Ellis, 2002; Weekes, 1997).”

• cites Lavidor and Ellis, 2002Not checked yet

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• cites Weekes, 1997 sourceNot checked yet

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The absence of a length effect is found only when the words are presented in the familiar horizontal format and within a restricted region of the fovea and right hemifield.

“Note that the absence of a length effect is found only when the words are presented in the familiar horizontal format and within a restricted region of the fovea and right hemifield (Lavidor and Ellis, 2002; Lavidor et al., 2001).”

• cites Lavidor and Ellis, 2002Not checked yet

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• cites Lavidor et al., 2001 sourceNot checked yet

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Some of the first evidence for a specific response to structured letter strings, as opposed to matched visual stimuli, came from PET.

“Indeed, some of the first evidence for a specific response to structured letter strings, as opposed to matched visual stimuli, came from PET (Petersen and Fiez, 1993; Petersen et al., 1990).”

• cites Petersen and Fiez, 1993Not checked yet

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• cites Petersen et al., 1990 sourceNot checked yet

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PET data remain appropriate to study functional rather anatomical specialization for word processing.

“PET data remain appropriate to study functional rather anatomical specialization for word processing.”

There is functional specialization for reading in the brain of literate human subjects.

“We propose that there is functional specialization for reading in the brain of literate human subjects.”

The computational requirements for invariant recognition are largely common to the recognition of any type of visual objects.

“Those computational requirements are largely common to the recognition of any type of visual objects: Tools, buildings, or faces can all appear with huge variations in their appearance, including size, location, orientation, and so on.”

• cites Riesenhuber and Poggio, 1999 sourceNot checked yet

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What constitutes a significant visual difference and what does not is defined culturally rather than visually.

“In general, however, what constitutes a significant visual difference and what does not is defined culturally rather than visually.”

The fast mapping of ''A'' and ''a'' onto the same abstract letter identity cannot be explained by generic features of the organization of the visual system.

“Thus, the fast mapping of ''A'' and ''a'' onto the same abstract letter identity cannot be explained by generic features of the organization of the visual system.”

This cortex is partially plastic and can, during ontogenesis, become progressively attuned to the requirements of reading.

“This cortex is partially plastic and can, during ontogenesis, become progressively attuned to the requirements of reading (McCandliss et al., 2003).”

• cites McCandliss et al., 2003 sourceNot checked yet

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The functional specialization for reading arises from a partial preemption or ''recycling'' of visual cortex which evolved for other purposes during phylogenesis.

“This should not be surprising because the functional specialization for reading arises from a partial preemption or ''recycling'' of visual cortex which evolved for other purposes during phylogenesis (Dehaene, 2004).”

• cites Dehaene, 2004Not checked yet

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In the case of reading, crucial aspects of the capacity of invariant recognition must be learned.

“In the case of reading, crucial aspects of this capacity of invariant recognition must be learned.”

At least part of the specialization for letter and word recognition occurs at retinotopically organized stages of visual processing.

“This suggests that at least part of the specialization for letter and word recognition occurs at retinotopically organized stages of visual processing (Nazir, 2000).”

• cites Nazir, 2000Not checked yet

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Individual sulci are known to vary at least up to 1 cm.

“This is especially true when the method is applied across different groups of subjects, although individual sulci are known to vary at least up to 1 cm (Sowell et al., 2002; Thompson et al., 1996).”

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• cites Thompson et al., 1996 sourceNot checked yet

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Only advanced experimental designs, such as the priming or adaptation method, are apt at proving the presence of shared circuitry.

“Only advanced experimental designs, such as the priming or adaptation method (Grill-Spector and Malach, 2001; Naccache and Dehaene, 2001), are apt at proving the presence of shared circuitry.”

• cites Grill-Spector and Malach, 2001Not checked yet

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• cites Naccache and Dehaene, 2001Not checked yet

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It is rather unlikely that the visual word area would have sharp borders that would delineate it qualitatively from other neighboring areas involved in face or object recognition.

“We also consider it rather unlikely that the visual word area would have sharp borders that would delineate it qualitatively from other neighboring areas involved in face or object recognition.”

In most subjects, the specialization for words is likely to be only partial.

“In most subjects, however, the specialization for words is likely to be only partial.”

We do not believe that there is a cytoarchitectonically defined subpart of the visual system that responds to visual words.

“We do not believe that there is a cytoarchitectonically defined subpart of the visual system that responds to visual words.”

Many of the mappings between upper case and lower case are arbitrary.

“Many of the mappings between upper case and lower case, for instance, are arbitrary.”

A generic visual recognition device is simply insufficient to account for the notation-dependent operations that are observed in skilled readers.

“A generic visual recognition device is simply insufficient to account for the notation-dependent operations that are observed in skilled readers.”

The acquisition of literacy modifies the brain network involved in speech repetition (especially for pseudo-words).

“It is known that the acquisition of literacy modifies the brain network involved in speech repetition (especially for pseudo-words, see Castro-Caldas et al., 1998).”

• cites Castro-Caldas et al., 1998 sourceNot checked yet

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In the present state of knowledge, it cannot be denied that small subregions of visual cortex show at least partial selectivity for letter strings.

“However, in the present state of knowledge, it cannot be denied that small subregions of visual cortex show at least partial selectivity for letter strings.”

The visual word form area must be carefully distinguished from more anterior regions that are increasingly cross-modal and engaged in semantic computations.

“Thus, we suggest that the visual word form area must be carefully distinguished from more anterior regions that are increasingly cross-modal and engaged in semantic computations.”

This does not preclude the possibility of its top-down activation by auditory words.

“This does not, however, preclude the possibility of its top-down activation by auditory words.”

Simple subtractions allow a more specific delineation of the VWFA.

“However, simple subtractions allow a more specific delineation of the VWFA.”

PET and fMRI studies are ill-adapted to resolve the issue of top-down or bottom-up posterior inferotemporal activations because they cannot resolve the fine temporal dynamics of neural activity.

“PET and FMRI studies are ill-adapted to resolve the issue of top-down or bottom-up posterior inferotemporal activations because they cannot resolve the fine temporal dynamics of neural activity.”

A dramatic interference of orthography on speech perception has been evidenced in a variety of behavioral tasks including rhyme detection, syllable monitoring, lexical decision, and phoneme monitoring.

“Furthemore, a dramatic interference of orthography on speech perception has been evidenced in a variety of behavioral tasks including rhyme detection (Donnenwerth-Nolan et al., 1981), syllable monitoring (Taft and Hambly, 1985), lexical decision (Ziegler and Ferrand, 1998), and phoneme monitoring.”

• cites Donnenwerth-Nolan et al., 1981 sourceNot checked yet

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• cites Taft and Hambly, 1985Not checked yet

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• cites Ziegler and Ferrand, 1998Not checked yet

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Even in patients with large lesions, combining lesions from multiple patients may allow identification of the necessary and sufficient regions reproducibly associated with pure alexia.

“Second, even in patients with large lesions, the combination of lesions from multiple patients may allow to identify the necessary and sufficient regions that are reproducibly associated with pure alexia.”

In that case, the lesion affected the expected region of the left mid-fusiform cortex, with an extension to the lateral edge of the lingual gyrus.

“The lesion affected the expected region of the left mid-fusiform cortex, with an extension to the lateral edge of the lingual gyrus.”

• cites Beversdorf et al., 1997Not checked yet

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Output projections from the VWFA to lateral language areas may be interrupted in parietal white matter, providing a plausible account for subangular alexia.

“Conversely, output projections from the VWFA to lateral language areas may be interrupted during their course in the parietal white matter, providing a plausible account for the so-called subangular alexia (Greenblatt, 1976; Iragui and Kritchevsky, 1991; Pirozzolo et al., 1981).”

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• cites Iragui and Kritchevsky, 1991Not checked yet

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• cites Pirozzolo et al., 1981 sourceNot checked yet

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More anterior fusiform cortex holds a location-invariant sublexical code.

“More anteriorily, priming became location invariant, though present for both words and their anagrams, suggesting a location-invariant sublexical code.”

Even assuming the fusiform was spared, these observations would not necessarily contradict the proposed model due to the possible contribution of white matter lesions.

“Even assuming that it was, these observations would not necessarily contradict the proposed model due to the possible contribution of white matter lesions.”

The VWFA computes the arbitrary mapping between upper- and lower-case letters.

“Third, there is also evidence that the VWFA computes the arbitrary mapping between upperand lower-case letters.”

Such a fine-grained specialization cannot be explained by a generic visual process.

“Such a fine-grained specialization cannot be explained by a generic visual process.”

Binder and Mohr (1992) delineated a critical region for pure alexia that fell within the left middle fusiform gyrus.

“The critical region fell within the left middle fusiform gyrus.”

• cites Binder and Mohr, 1992Not checked yet

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In the most severe cases, known as global alexia, pure alexic patients cannot even identify single letters.

“In the most severe cases, known as global alexia, they cannot even identify single letters (Dejerine, 1892).”

• cites Dejerine, 1892Not checked yet

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Alexia restricted to the left half of the visual field results from lesions of posterior callosal pathways.

“The clearest example of such a deafferentation is the alexia restricted to the left half of the visual field which results from lesions of posterior callosal pathways (Suzuki et al., 1998).”

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White matter lesions may blur anatomo-functional correlations.

“A factor that may blur anatomo-functional correlations is the role of white matter lesions.”

The middle fusiform gyrus contains units larger than the letter level.

“Finally, even more anteriorily in the middle fusiform gyrus, there was a trend towards greater priming when the same word was presented twice compared to when it was preceded by an anagram, suggesting the presence of the units larger than the letter level.”

Simple considerations on the input and output pathways of the VWFA provide a detailed and consistent explanation for the variety of visual alexias seen in adult neuropsychological cases.

“Altogether, simple considerations on the input and output pathways of the VWFA provide a detailed and consistent explanation for the variety of visual alexias seen in adult neuropsychological cases (Cohen et al., 2003).”

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No firm anatomical argument, positive or negative, can be made from Warrington and Shallice's cases.

“Thus, no firm anatomical argument, positive or negative, can be made from Warrington and Shallice's cases.”

The simplest account of pure alexia is that it reflects a breakdown of the visual word form system.

“The simplest account of pure alexia is that it reflects a breakdown of the visual word form system (Cohen et al., 2000; Warrington and Shallice, 1980).”

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• cites Warrington and Shallice, 1980Not checked yet

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The anatomical case reported by Greenblatt (1973) may be an instance of complete deafferentation of an intact fusiform cortex.

“Finally, the anatomical case reported by Greenblatt (1973) may be an instance of complete deafferentation of an intact fusiform cortex (see also Cohen et al., submitted for publication).”

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• cites Cohen et al., submitted for publicationNot checked yet

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The posterior subpart of mid-fusiform cortex likely holds a location-specific sublexical code.

“Thus, this region likely holds a location-specific sublexical code.”

This suggests that the VWFA has become sensitive to orthographic rules in the subject's language, which are matters of cultural convention.

“This suggests that it has become sensitive to orthographic rules in the subject's language, which are matters of cultural convention.”

Associations of deficits provide only a weak source of constraints.

“However, such associations of deficits are known to provide only a weak source of constraints (Shallice, 1988).”

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Binder and Mohr (1992), Damasio and Damasio (1983), and Cohen et al. (2003) agree on the lateral edge of the left fusiform gyrus as associated with pure alexia.

“Such work was done by Binder and Mohr (1992), Damasio and Damasio (1983), and more recently by our group (Cohen et al., 2003), with a good agreement of these studies on the lateral edge of the left fusiform gyrus.”

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• cites Damasio and Damasio, 1983 sourceNot checked yet

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• cites Cohen et al., 2003 sourceNot checked yet

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Not all pure alexic patients have extensive lesions blurring anatomical correlations.

“First, not all patients have extensive lesions blurring anatomical correlations.”

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The intermingling of such neurons with others coding for objects or faces would translate into a partial regional selectivity at the single-voxel level, which is all that can presently be measured with PET or fMRI.

“The intermingling of such neurons with others coding for objects or faces would translate into a partial regional selectivity at the single-voxel level, which is all that we can presently measure with PET or fMRI.”

Because the VWFA may contain cortical columns specialized for letter processing mixed with columns with different preferences, disruption of the VWFA would likely induce some degree of impairment beyond reading.

“Given that the VWFA may contain cortical columns specialized for letter processing, mixed with columns with different preferences (Puce et al., 1999), it is likely that a disruption of the VWFA would induce some degree of impairment beyond reading (Behrmann et al., 1998a).”

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• cites Behrmann et al., 1998aNot checked yet

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The reproducible localization of the VWFA indicates that only a small subregion of visual cortex has the optimal initial characteristics that permit it to be preempted or recycled for reading.

“We tentatively suggest that the reproducible localization of the VWFA indicates that only a small subregion of visual cortex has the optimal initial characteristics that permit it to be preempted or ''recycled'' for reading (Dehaene, 2004).”

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P&D's hypothesis that reading is more complex and imposes greater demands on visual processing is not sufficiently articulate to account for double dissociations such as object agnosia without alexia or prosopagnosia without alexia.

“is not sufficiently articulate to account for double dissociations such as object agnosia without alexia (Albert et al., 1975; Gomori and Hawryluk, 1984) or prosopagnosia without alexia (e.g. McNeil and Warrington, 1993).”

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• cites Gomori and Hawryluk, 1984Not checked yet

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• cites McNeil and Warrington, 1993Not checked yet

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Impaired identification of even single letters is common in pure alexia, ranging in severity from complete global alexia to occasional errors with significant slowing of letter naming.

“Furthermore, impaired identification of even single letters is common in pure alexia, ranging in severity from complete global alexia to the occurrence of occasional errors with a significant slowing down of letter naming (for a review, see Behrmann et al., 1998b; e.g. Hanley and Kay, 1996).”

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• cites Hanley and Kay, 1996Not checked yet

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Such neurophysiological mechanisms may provide a neuronal basis for the acquisition of invariant visual word recognition in humans.

“Such neurophysiological mechanisms may provide a neuronal basis for the acquisition of invariant visual word recognition in humans.”

Binding of letters may also be based on more holistic coding, as suggested by the demonstration that single IT neurons develop selectivity for learned complex shapes above and beyond additive influence of component parts.

“Binding of letters may also be based on more holistic coding, as suggested by the recent demonstration that single IT neurons develop selectivity for learned complex shapes, above and beyond what could be expected from the additive influence of their component parts (Baker et al., 2002).”

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Such observations predict the existence of highly specialized but patchy and distributed neuronal populations coding for alphabetic stimuli at the single-neuron level.

“Such observations predict the existence of highly specialized but patchy and distributed neuronal populations coding for alphabetic stimuli at the single-neuron level.”

It is unclear how general accounts may account for the frequent sparing of recognition of complex multipart objects, faces, or digit strings in pure alexic patients.

“However, it is unclear how this may account for the frequent sparing of the recognition of complex multipart objects, faces, or digit strings in pure alexic patients.”

The conjunction of these factors may collectively conspire to define a cortical region optimally apt at hosting the functional processes of visual word recognition.

“The conjunction of these factors may collectively conspire to define a cortical region optimally apt at hosting the functional processes of visual word recognition.”

The ability of IT neurons to learn arbitrary shapes and pairings might be an analogue of learning letters and of linking arbitrarily related upper- and lowercase letters.

“IT neurons are able to learn new arbitrary shapes (Logothetis et al., 1995), and arbitrary pairings of stimuli (Sakai and Miyashita, 1991), which might be an analogue of learning letters and of linking arbitrarily related upper- and lowercase letters.”

Even if there is a cortical sector highly selective for alphabetic stimuli, a spontaneous lesion would be unlikely to affect it with perfect selectivity while sparing adjacent cortex.

“Even assuming that there is a cortical sector highly selective for the perception of alphabetic stimuli, it would be unlikely that a spontaneous lesion should affect this region with perfect selectivity although sparing the adjacent cortex.”

This symptom presents a real challenge to nonspecific theories of pure alexia because it is difficult to argue that single letters are more complex than faces or drawings of objects.

“This symptom presents a real challenge to nonspecific theories of pure alexia because it is difficult to argue that single letters are in any sense more complex than faces or drawings of objects.”

It is hardly surprising that some degree of associated visual impairment can be evidenced in most alexic patients.

“Thus, it is hardly surprising that some degree of associated visual impairment can be evidenced in most alexic patients.”

Visual word recognition therefore necessarily makes use of preexisting primate circuitry.

“Visual word recognition therefore necessarily makes use of preexisting primate circuitry.”

Warrington and Shallice (1980) and Patterson and Kay (1982) showed that patients with letter-by-letter reading could accurately report digits flanking a letter string even when stimuli were flashed for 150 ms and comprised as many as eight intervening letters.

“For instance, as an argument against a general impairment of parallel visual processing, Warrington and Shallice (1980) and Patterson and Kay (1982) showed that patients with letter-by-letter reading could accurately report digits flanking a letter string (e.g. 6APPLE4), even when such stimuli were flashed for 150 ms and comprised as many as eight intervening letters.”

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• cites Patterson and Kay, 1982Not checked yet

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The dissociation between letters and digits in pure alexia dates back to Dejerine's observation that the patient recognizes very well all digits although he cannot recognize a single letter.

“This dissociation between letters and digits in pure alexia dates back to Dejerine's observation, as he noted that ''the patient recognizes very well all digits'', although ''he cannot recognize a single letter'' (Cohen and Dehaene, 1995; Dejerine, 1892; Holender and Peereman, 1987; for imaging data, see also Pinel et al., 2001; Polk et al., 2002).”

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• cites Dejerine, 1892Not checked yet

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• cites Holender and Peereman, 1987Not checked yet

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During the acquisition of literacy, the VWFA incorporates script- or language-specific arbitrary regularities.

“We propose that during the acquisition of literacy, the VWFA incorporates script- or language-specific arbitrary regularities.”

In the macaque perirhinal cortex, specific visual experience induces development of clusters of neurons with similar stimulus preferences.

“In the macaque perirhinal cortex, specific visual experience induces development of clusters of neurons with similar stimulus preferences (Erickson et al., 2000).”

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There is presently no complete account of pure alexia in terms of a general visual problem.

“However, we believe that there is presently no complete account of pure alexia in terms of a ''general visual problem''.”

The binding of letters into words might be related to the representation of complex objects in IT cortex through the coactivation of neurons tuned to their elementary parts.

“Likewise, the binding of letters into words might be related to the representation of complex objects in IT cortex through the coactivation of neurons tuned to their elementary parts (Tsunoda et al., 2001).”

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Chanoine et al. (1998) reported closely similar findings in another patient.

“Chanoine et al. (1998) reported closely similar findings in another patient.”

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Such features of pure alexia cannot be plausibly accounted for from nonspecific perceptual impairments.

“Such features of pure alexia cannot be plausibly accounted for from nonspecific perceptual impairments.”