Functional Foveal Splitting: Evidence from
Neuropsychological and Multimodal MRI Investigations
in a Chinese Patient with a Splenium Lesion
Benyan Luo1, Chunlei Shan2*, Renjing Zhu3, Xuchu Weng4,5, Sheng He6
1 Department of Neurology, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China, 2 Department of Rehabilitation Medicine, First Affiliated
Hospital of Nanjing Medical University, Nanjing, China, 3 Department of Neurology, Zhongshan Hospital, Xiamen University, Xiamen, China, 4 Key Laboratory of Mental
Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China, 5 The Center for Human Brain Research, Hangzhou Normal University, Hangzhou, China,
6 Department of Psychology, University of Minnesota, Minneapolis, Minnesota, United States of America

Abstract
It remains controversial and hotly debated whether foveal information is double-projected to both hemispheres or split at
the midline between the two hemispheres. We investigated this issue in a unique patient with lesions in the splenium of the
corpus callosum and the left medial occipitotemporal region, through a series of neuropsychological tests and multimodal
MRI scans. Behavioral experiments showed that (1) the patient had difficulties in reading simple and compound Chinese
characters when they were presented in the foveal but left to the fixation, (2) he failed to recognize the left component of
compound characters when the compound characters were presented in the central foveal field, (3) his judgments of the
gender of centrally presented chimeric faces were exclusively based on the left half-face and he was unaware that the faces
were chimeric. Functional MRI data showed that Chinese characters, only when presented in the right foveal field but not in
the left foveal field, activated a region in the left occipitotemporal sulcus in the mid-fusiform, which is recognized as visual
word form area. Together with existing evidence in the literature, results of the current study suggest that the
representation of foveal stimuli is functionally split at object processing levels.
Citation: Luo B, Shan C, Zhu R, Weng X, He S (2011) Functional Foveal Splitting: Evidence from Neuropsychological and Multimodal MRI Investigations in a
Chinese Patient with a Splenium Lesion. PLoS ONE 6(8): e23997. doi:10.1371/journal.pone.0023997
Editor: Yong He, Beijing Normal University, China
Received January 15, 2011; Accepted August 2, 2011; Published August 26, 2011
Copyright: ß 2011 Luo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported by 1. National Natural Science Foundation, No. 31070905 (http://www.nsfc.gov.cn/Portal0/default106.htm); 2. Chinese
Ministry of Science and Technology, No. 2007CB512300 (http://www.most.gov.cn/eng/); 3. NSF grant BCS-0818588(www.nsf.gov). The funders had no role in
study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: shanclhappy@163.com

The second theory, often called the ‘‘split-fovea theory’’ (SFT),
states that each half of the fovea is divided precisely at its vertical
midline and visual information is exclusively projected to the
contralateral visual cortex [24–48]. The most important line of
evidence supporting this theory comes from studies on visual word
processing. These studies showed that functional hemispheric
differences, which used to be demonstrated by parafoveal
presentation, can also be readily observed in foveal presentation
conditions with a variety of experimental manipulations [34], as
indicated by the optimal viewing position effect [24–25,31], the
word length effect [32,37], case alternation effects [49], and the
orthographic neighborhood effect [27,34]. Most recently, following the SERIOL model of visual word recognition [50], Haegen &
Brysbaert provided further evidence for SFT by investigation of
interhemispheric inhibition in the processing of visual word
integration [51].
It should be noted that many of the studies on foveal
representations are conducted in healthy subjects or patients with
functionally and anatomically intact corpus callosum, which could
make it difficult to make straightforward inferences about foveal
representation in the two hemispheres. For example, there is the
possibility that, even if there are bilateral projections (thus double
cortical representations for foveal information), which the BPT
assumes, the ipsilateral representation could be subordinated to

Introduction
There are two competing theories regarding the cortical
representation of the foveal vision, which is crucially important
for many visual tasks such as reading and face recognition. The
first theory, often referred to the ‘‘bilateral projection theory’’
(BPT), proposes that the foveal information from the left and right
visual fields (LVF and RVF) overlaps along the vertical meridian
and two complete copies of a foveally presented visual stimulus are
projected in parallel to the early visual cortex of each hemisphere.
This theory is supported by a number of physiological and
anatomical studies in laboratory animals [1–7], as well as
behavioral studies in hemianopia patients showing macular or
foveal sparing and in commissurotomized patients showing better
performance for foveal presentation than para-foveal/peripheral
presentation in tasks relying on the integration of left and right
visual field information [8–14]. More recently, Marzi et al.
indicated bilateral representation of the fovea in healthy individuals by using the Poffenberger paradigm and monocular vision
[15]. In a series of carefully designed experiments, Jordan et al.
[16–20] reported negative evidence for a functional division in
hemispheric processing at foveal field. In addition, some results of
functional brain imaging studies also appear to be consistent with
the BPT [21–23].
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Foveal Splitting in a Splenium Lesioned Patient

the contralateral one and behavioral manifestation might be
dominated or masked by contralateral information through corpus
callosum inhibition [52–53] (see review of Bloom & Hynd [54]).
On the other hand, even if the information in one half foveal field
is initially projected only to the contralateral visual cortex as the
SFT assumes, it could still be received slightly later by the
ipsilateral visual cortex through quick splenium transfer. This
effect is too fast to detect in many experimental conditions, except
in some carefully designed experiments [55–58]. Therefore,
subjects with disconnected communications between posterior
hemispheres, such as patients with splenium lesion or commissurotomy, provide a unique opportunity to tease apart mixed
accounts for cortical representations of foveal vision. Sieroff &
Lavidor adopted reading tasks to test a patient with left medial
occipital lesion which the author suggested to injure the splenium,
and found evidence supporting SFT [59]. Unfortunately the
authors did not use relatively direct imaging methods such as high
resolution structural image or DTT (diffusion-tensor tractography)
to confirm the disruption of the splenium. And, the words or
pseudowords presented in LFF or RFF subtended a visual angle of
2 degree, larger than the maximum size of one half of foveal field
(the central fovea is 1u–3u[2–3,10,29], half fovea should be 0.5u–
1.5u).
In the present study, we studied a patient with a lesion in the
splenium to explicitly test the BPT and SFT, using various
experimental manipulations and with combined use of high
resolution structural and functional MRI (fMRI), and diffusion
tensor imaging (DTI) techniques. Multimodal MRI data would
allow us to perform a detailed lesion analysis, by which the loci
and degrees of lesions in both the gray and white matter of the
patient’s brain could be accurately evaluated.
Another merit of this study is that the patient was premorbidly a
skilled Chinese reader. The majority of Chinese characters are leftright structured compounds, with one component on the left and
the other on the right. There are two types of left-right structured
compound characters. About 90% are semantic- phonetic
characters (SP), in which the left component indicates the meaning
of the whole character, whereas the right one provides a cue to the
pronunciation of the character. About 10% of left-right structured
compound characters are phonetic-semantic characters (PS), in
which the left component provides phonetic information about the
character and the right suggests the character’s meaning. In both
SP and PS, the semantic and phonological relationship between a
character and the components that form this character is often
subtle and not always reliable [41]. It should be noted that the
stroke number of semantic components is typically smaller than
that of phonetic components and the ratio of SP to PS character
types is about nine to one. In other words, the left and right
components in a character could remarkably differ in terms of
visual complexity, occurrence frequency, and information density,
which consequently may influence readers’ attention and perception to the left and right components. In the behavioral
Experiment 1, we used the same number of SP and PS characters
(30 for each type) to control for the possible confounding.
Furthermore, the semantic and phonetic components themselves
are often simple characters with their own pronunciation and
meaning [60–62]. These features make Chinese characters
particularly suitable for addressing whether or not visual
information is fovea-split, because the left and right components
can be presented precisely within the left and right foveal field
(LFF and RFF) respectively and tested separately at the
component level or jointly at the whole character level [40–42].
Thus to test foveal representation in the brain, Chinese characters
have an advantage over alphabetic words. In the latter there is
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often no clear (visual, semantic, or phonological) boundary
between the left and right parts within a written word, particularly
the short-length word consisting of only a few letters (unfortunately, such words are commonly used in previous studies).
Furthermore, because a Chinese character occupies a constant
square-shaped space with the approximately same size, a whole
character can be presented completely within a half foveal field
(the visual angle of a character in normal reading texts is about
0.5u or less in both horizontal and vertical dimensions). This allows
us to test the patient’s reading performance in a variety of
presentation conditions. We predict that, if the SFT is correct, our
patient would be unable to correctly read the Chinese characters
presented either in the central or in the LFF. This is because the
information from the LFF (left components in the central
condition or whole characters presented in the LFF), according
to the SFT, is exclusively projected to the right visual cortex and
cannot be transferred to the visual word form area (VWFA), a
critical region for visual word recognition in the left lateral midfusiform [63–65]. If the BPT is correct, however, he should be able
to read the foveally presented characters regardless which field the
stimuli are presented, because all visual information of the
presented character can be transferred to both hemispheres
according to this theory.
Critically, for a good theory that genuinely describes the
organizations and computations of the visual system, it must apply
to a wide range of visual processes, not limited to reading tasks
(See [30,35] for more detailed discussion). We thus carefully
designed a face recognition task, in which the patient was asked to
make gender judgment while a chimeric face (composed of a half
male face and a half female face) was presented entirely within the
foveal field, with half face in the LFF and another half in the RFF.
Because face recognition relies more on the right hemisphere
[66–71] and the patient’s left fusiform was damaged, we predict
that, if the SFT is correct, his judgment would exclusively be based
on the information from the half face left of the fixation. In
contrast, if the BPT is correct, the information of both parts of the
chimeric face would be sent to the fusiform face area (FFA) in the
right fusiform gyrus [69,72], and the patient would be able to see
that the faces are chimeric.
Finally, to measure brain responses to the visual stimuli
presented to the left or right regions within the foveal field, thus
offering a more direct test for the BPT and SFT, we further
conducted an fMRI experiment, in which Chinese characters were
presented in the LFF or RFF. The SFT would predict that stimuli
presented in the LFF activate the right early visual cortex while the
left early visual cortex and the VWFA in the left fusiform would
not be activated, due to the interruption of the splenium. In
contrast, the BPT would predict that the early visual cortex in both
hemispheres, as well as the VWFA in the left fusiform cortex,
would be significantly activated regardless of LFF or RFF
presentation of stimuli.

Methods
Case description
The patient was a right-handed Native Chinese, male and 80
years old, with 16 years of education. He had a stroke with a
sudden onset of a blurred vision and light numbness over his left
limbs in July of 2003. At that time he also complained about
reading difficulties. Common therapies for stroke patients were
administered following the first month of his stroke onset.
Thereafter, he stayed in a sanitarium and regularly took oral
medicines. In February of 2007, he was admitted to the 1st
affiliated hospital of Nanjing Medical University and complained
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Foveal Splitting in a Splenium Lesioned Patient

25.3 ms, flip angle = 90u, field of view = 2406240 mm, matrix = 2566256, slice-thickness = 5 mm, gap = 0 mm. (2) SPGR:
116 axial images, covering total cerebrum and most cerebellum,
were collected with the following parameters: TR = 25 ms,
TE = 3.8 ms, flip angle = 20u, field of view = 2406240 mm,
matrix = 2566256, slice-thickness = 1 mm, gap = 0 mm. (3) DTI
images: 35 axial diffusion-weighted single-shot spin-echo echo
planar imaging (SE-EPI) were acquired with the following
parameters: TR = 9000 ms, TE = 79.7 ms, field of view =
2406240 mm, matrix = 96696, slice-thickness = 3 mm, gap =
0 mm, in-plane resolution = 0.9460.94 mm, 15 gradient directions, b-values = 0 and 1000 s/mm2.
Diffusion tensors, fractional anisotropy (FA), and fiber tracts
were calculated using volume-one 1.64 and diffusion tensor
visualizer II (dTV II) software (Department of Radiology, Tokyo
University School of Medicine). Standard methods for FA
exclusion and tracking algorithms were used with a minimum
FA of 0.18 and maximum angle of 30u. We identified the splenium
on the mid-sagittal plane [76] and used it as an ROI (region of
interest) to reconstruct fiber tracts going through the splenium.
SE-T1 weighted (Figure 1, A, B, C) and SE-T2 weighted
(Figure 1, D) axial MRIs, T1-FLAIR (Figure 1, E, F, G ), SPGR
(Figure 1, H), and DTT (Figure 2) converge to indicate that the
patient had infarctions in the left ventral medial occipitotemporal
cortex, involving most parts of the left lingual gyrus, cuneus gyrus
and fusiform gyrus, and the left splenium of the corpus callosum,
extending to the left major forceps (Figure 1, C, D and G).
Note that the left lateral mid-fusiform region, medial to the left
occipitotemporal sulcus, was preserved (Figure 1, F, H). This
region corresponds precisely to the location of the VWFA in the
literature [63,77].
Relative to the MRIs taken 3 years ago (Figure 1, C, D), the T1FLAIR images (G) showed, due to liquefaction of the infarction,
the left major forceps became thinner and the posterior horn of left
lateral ventricle became slightly larger.
The T2 weighted images (Figure 1, D) clearly show the
infarction in the splenium. The fiber tracking analysis further

of reading problem for about three years post-onset. Neurological
examination revealed a right homonyous hemianopsia. The MRIs
(January, 2004) showed that he had lesions involving the left
occipitotemporal cortex and the left splenium of the corpus
callosum (for details, see Lesion Analysis below). Neuropsychological assessments showed that the patient was unable to identify the
left component of Chinese characters, a symptom similar to the
cases reported by Binder et al. [73] in alphabetic readers (the
authors labeled this symptom as left hemiparalexia). The patient
often misread Chinese character as another one that shares the
same right component as the target. For example, he misread
(/deng 1/, lamp) as
(/da 3/, beat), and
(/zhi 4/, order) as
(/tie 3/, iron). Visual perimetry confirmed a right homonymous hemianopia but with 1.5u of foveal sparing. The Line
Bisection Test [74] and Albert Cancellation Test [75] showed no
sign of visual hemineglect. According to the assessments with the
Chinese version of Western Aphasia Battery, the patient was not
aphasic; his Aphasia Quotient was 97.8 (cutoff: 93.8). He scored 27
on mini-mental state examination (MMSE, cutoff: 24).
Two healthy men (both were 80 years old and with
approximately the same educational experience with KY) served
as normal controls in the behavioral experiments.
The study was approved by the Ethics Committee of the First
Affiliated Hospital of Nanjing Medical University. The patient and
the normal controls gave written informed consent prior to their
participation in the study according to the Declaration of Helsinki,
and they also provided written informed consent (as outlined in the
PLoS consent form) to publication of their case details.

Lesion analysis
In addition to the clinical MRI films taken in 2004, we acquired
high contrast and high resolution structural and DTI images of the
patient’s brain to more accurately evaluate the lesions, particularly
the splenium of the corpus callosum and occipitotemporal regions.
Three types of images were acquired on a 1.5 Tesla Signa Imager
(GE, Milwaukee, USA). (1) T1-FLAIR: 23 axial images were
acquired with the following parameters: TR = 2019.3 ms, TE =

Figure 1. Lesions and intact VWFA shown in the structural MRI of the patient’s brain. The red arrows indicate the infarctions in the left
ventral medial occipitotemporal cortex (A, B, E and F) and the left splenium of the corpus callosum extending to the left major forceps (C, D and G).
The yellow arrow indicates the intact left lateral mid-fusiform cortex and occipitotemporal sulcus (F and H). The VWFA is highlighted with the green
crosshair (Talairach coordinates: x = 243, y = 254, z = 212) in a coronal slice of spatially normalized SPGR images (H).
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randomly (each for 180 ms) in the LFF or RFF. Each simple
character subtended about 0.8 degree of visual angle with the
external edge at 1.0 degree to the fixation point, and each
compound character subtended about 1.3 degree of visual angle
with the external edge at 1.5 degree excentric to the fixation point
(Figure 3, B, C). The patient was asked to fixate at the fixation
point continuously and read aloud each character.
Experiment 3. This experiment aimed at exploring whether a
face (a stimulus type rarely tested in the foveal representation domain)
is double-projected to the bilateral visual cortices when it is presented
in the foveal field. Twenty chimeric faces were used, 10 of them with
male half-face on the left and female half-face on the right, and the
other 10 were aligned conversely. Each half of a chimeric face
subtended no more than 1.2 degree of visual angle (Figure 4). Each
chimeric face was presented for 180 ms. The patient was asked to
fixate continuously at the fixation point, which appeared at the
middle of the chimeric face, and to report whether the stimulus was a
male or a female face [66]. He was also asked to rate his confidence
about his decision at three levels: high, modest, and no confidence.

delineated that the white matter fiber tracts going through the
splenium was interrupted (Figure 2, B), whereas the tracts in the
normal control was intact.

Behavioral experiments
Experiment 1. Sixty left-right structured Chinese characters
(subtended about 1.5 degree of visual angle) were presented
centered at the fixation, each for 180 ms. To ensure that the left
and right components of a character were projected onto right and
left half of the fovea respectively, the patient was required to fixate
continuously to a fixation point at the middle between the left and
right components and read aloud each character (Figure 3, A). To
avoid possible attentional bias caused by the differences of
complexity between the left and right components (see Note 1
and [42]), we used equal numbers of SP characters (the semantic
radical on the left and the phonetic radical on the right) and PS
characters (the phonetic radical on the left and the semantic
radical on the right), each type consisted of 30 characters. There
was no difference between the two types of characters with respect
to the frequency (Language and Teaching Institute of Beijing
Linguistic College, 1986) and complexity (measured as the number
of strokes) of the whole characters (p.0.05, for both measures).
Take into consideration the prevalence of homophones in
Chinese characters, in Experiment 1 and 2, the patient was asked
to make a word consisting of the character he read (word forming),
to confirm whether the patient recognized the characters correctly
or incorrectly (to disambiguate from possible homophone
character). For example, after the patient read the character
(zhi1/know)with ‘‘zhi1’’, he was required to make a word with the
/know), it
character he recognized. If he said ‘‘zhi1 dao4’’ (
would be coded as correct. If he said ‘‘zhi1 bu4’’ (
/weaving),
although the same pronunciation (zhi 1), it would be coded as an
error. Since KY could made words correctly from characters he
heard or he wrote, it is very unlikely that he made words
incorrectly if he read characters correctly.
Experiment 2. In order to control for the possible neglect of
the left or right components when they were simultaneously
presented in the left and right foveal fields in Experiment 1, we
used 36 simple characters (consist of one component) and 128 leftright structured compound characters in this experiment. These
characters, matched for frequency and complexity, were presented

Statistical analysis
For behavioral results, the key comparison was on the difference
between the LFF and RFF condition in response accuracy for
recognizing characters and components as well as chimeric face
gender judgment. The statistical significance of these differences
was tested with Chi-Square test (SPSS, Version 11.5 ).

fMRI experiment
This experiment was similar to that used by Cohen et al. [63].
However, there were important differences between two studies.
First, Chinese compound characters rather than English words
were adopted in our study. Second and more importantly, all
stimuli were presented within the foveal field (,1.2 degree
eccentricity) in this experiment, but the mean eccentricity of the
stimuli was 4.9u, i.e., outside the foveal region, in the study of
Cohen et al. [63].
Stimuli. The stimuli were 80 left-right structured compound
characters (each consisted of 2 to 4 radicals and 6 to 11 strokes).
All characters were highly imaginable common nouns with high
frequency. These characters were grouped into two lists, 40
characters each, matched one-to-one for the numbers of strokes

Figure 2. DTI fiber tracking images of the splenium of the patient and a normal control. The fiber tracking was calculated based on an ROI
(marked with red circle) covering the splenium in the midsagittal plane (A). B and C show the fiber tracts through the splenium in the patient and a
healthy control respectively. The yellow arrows indicate the major forceps fibers and the light blue arrows indicate the tapetum.
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Figure 3. Examples of compound and simple characters used in Experiment 1 and Experiment 2. A. Example of the two types of leftright structured Chinese characters presented centrally to the foveal field (behavioral Experiment 1.). Note that the left and right components were
presented completely within the left and right halves of the foveal field; the red dot between the left and right components is the fixation point.
B. Divided visual field presentation of simple characters (behavioral Experiment 2). Note that the whole character was presented either within the left
or right foveal field; the red dot is the fixation point. C. Divided visual field presentation of compound characters (behavioral Experiment 2). Note that
the whole character was presented either within the left or right foveal field; the red dot is the fixation point.
doi:10.1371/journal.pone.0023997.g003

10 trials (a block). Each character appeared twice, once in the RFF
block and once in the LFF block. The medial and lateral edges of
each character were 0.2u and 1.2u from the fixation point
respectively (Figure 5). The patient was asked to fixate at a
continuously present central cross-hair and to read characters
silently whenever he saw the characters on the screen.
Imaging acquisition and analysis. 23 axial functional
images were acquired with a T2*-weighted gradient-echo, echo
planar imaging (EPI) sequence on the GE 1.5 Tesla scanner
[TR = 2000 ms, TE = 40 ms, flip angle = 90u, field of view =
2406240 mm, thickness = 5 mm, gap = 0 mm, in-plane resolution = 3.7563.75 mm, 120 volumes for each run]. T1-FLAIR and
3D- SPGR Image were also acquired for anatomical localization
(see the Lesion Analysis section).
The AFNI package (Cox 1996, http://afni.nimh.nih.gov/afni/)
[78] was used for image display and data analysis. The first 10

and radicals. The two lists were also matched for overall
frequency. Each list was further divided into four sets, 10
characters for each. Two sets, one from each list, formed one
pair. Two sets characters of the same pair were matched one-toone for the numbers of radicals and strokes and overall frequency.
By doing so, we created four pairs (8 sets: a and a9, b and b9, c and
c9, d and d9) of stimuli, and each set consisted of 10 characters.
Stimulus parameters, task, and procedures. Four fMRI
runs were performed; each consisted of an alternation of activation
blocks (40 s) and fixation blocks (40 s), starting with a 20 s fixation
epoch to allow T1 equilibration (Figure 5). During the activation
blocks, Chinese characters flashed either into the patient’s RFF or
LFF. There were 10 trials in each activation block. Each trial
began with a fixation epoch of 3820 ms and followed by a
presentation epoch, in which each character was presented for
180 ms. The characters were shuffled randomly within each set of

Figure 4. An example of the chimeric faces and its possible representations in the patient’s two hemispheres. A. According to SFT, the
information of the left half of the chimeric face (left to the fixation, half of a female face, upper panel) is exclusively projected to the right hemisphere
(RH) and that of the right half of the chimeric face (right to the fixation, half of a male face, upper panel) is exclusively projected to the left
hemisphere (LH). Because face recognition is right hemispheric dominant, the patients with interrupted splenium of the corpus callosum would make
a gender judgment by the left part of the chimeric face (in this case, the patient would judge the chimeric face as a whole female face, owing to
‘‘hallucinated completions’’ of faces. [ Levy, Trevarthen and Sperry, 1972; Trevarthen and Kinsbourne, 1972] ). B. According to BPT, the information of
the left half as well as right half of the chimeric face (upper panel) are projected simultaneously to both RH and LH. The patient would see both parts
of the chimeric face.
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condition was estimated and multiple regressions were calculated
for each voxel to test the fitness between the observed time series
and the estimated response. Those voxels whose F values were
equal to or greater than threshold (P = 0.05, corrected (FDR)) were
defined as task-relevant, and were superimposed on the anatomic
images to produce activation map for each condition.

Results
Behavioral experiments
The results of three behavioral experiments are summarized in
Table 1.
Experiment 1. This experiment was designed to examine the
patient’s reading performance when Chinese compound
characters were briefly presented in the central foveal field. In
this condition, the patient could correctly read out only 14 of 60
characters tested (the accuracy for the PS characters was not
significantly different from that for the SP characters; we therefore
pooled together the two types of characters in the subsequent
analyses). Among the 46 characters he could not correctly read, 38
were misread and 8 were unrecognized. His reading problem was
mostly resulted from his difficulty in identifying the left
components. Indeed, among the 38 characters he misread, two
were misread because of the omission of the left components (he
read the right components as the names of the characters), For
example, he read
(/yuan 4/, yard) as
(/wan 2/, finish) and
read
(/ti 4/, tears) as
(/di 4/, brother). 26 were substituted
by different characters that contain the same right components but
with different left components as the tested characters. In other
words, the left components of these 26 characters were substituted
rather than omitted. For example,
(/yin 3/, drink) was misread
as
(/chui 1/, blow),
(/zhao 3/, search) as
(/xi 4/, game).
The remaining 10 characters were recognized as characters with
similar shape, such as
(/dong 4/, move) as
(/chu 1/,
beginning),
(/shi, 4/, watch) as
(/zhen 3/, pillow).
For KY, the correct rates of recognition of the left and right
component were 14/60(23%) and 44/60(73%) respectively. The
difference was significant (x2(1) = 30.0, p = 0.000 ) (Table 1). The
two normal controls correctly recognized all the tested stimuli.

Figure 5. Schematic depiction of the fMRI experimental
paradigm and examples of two types of stimuli. Upper panel:
fMRI experimental paradigm (only the first run is shown); lower panel:
examples of two types of stimuli presented in the LFF or RFF. +: fixation
point; a/a9 and b/b9: two paired characters lists, matched one-to-one for
the numbers of strokes, radicals, and overall frequency.
doi:10.1371/journal.pone.0023997.g005

volumes in each run were discarded, leaving a total of 480 EPI
volumes that were analyzed for brain activation. The 3D-SPGR
data was normalized to the standardized space of Talairach and
Tournoux [79]. Functional MR images were motion-corrected
and smoothed with an isotropic Gaussian kernel (FWHM = 3 mm)
to enhance the signal-to-noise ratio. Using the 3-D deconvolution
program of AFNI, the impulse response function for each

Table 1. Summary of the results of three behavioral experiments.

Experiment 1

Experiment 2

Experiment 3

Reading

Gender judgment

compound characters
in the central fovea

simple characters
in the LFF/ RFF

compound characters
in the LFF/ RFF

Chimeric face in
the central fovea

Whole characters

14/60(23%)

—

—

—

Components (Characters)
in LFF (Correct rate, %)

14/60(23%)

8/18(44%)

0/64(0%)

—

Components (Characters)
in RFF (Correct rate, %)

44/60(73%)A

17/18(94%)B

33/64(52%)C

—

Judged as the gender
of the left half face (%)

—

—

—

17/20 (85%)

Judged as the gender
of the right half face (%)

—

—

—

3/20 (15%)D

Note: LFF = left foveal field, RFF = right foveal field; * LFF versus RFF,
Ax2(1) = 30.0, p = 0.000;
Bx2(1) = 10.6, p = 0.003;
Cx2(1) = 44.5, p = 0.000;
Dx2(1) = 19.6, p = 0.000.
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Foveal Splitting in a Splenium Lesioned Patient

Experiment 2. This experiment was to test the patient’s
performance of reading whole characters presented entirely within
the LFF or RFF. Relative to the RFF condition, he showed much
severer deficits in reading aloud and recognizing the characters
that were presented in the LFF (simple character: x2(1) = 10.6,
p = 0.003; compound characters: x2(1) = 44.5, p = 0.000), with the
scores for simple characters being slightly higher than for the
compound characters (see Table 1). This difficulty in reading
characters in the left visual field was consistent with left
hemialexia, reported in alphabetic languages [63,64,80]. The
patient also showed a symptom of perseveration when he read
compound characters presented in the LFF. For example, he
misread more than 10 characters as the same character, i.e.,
(/
dian 4/, sediment), in a stereotyped manner.
The two normal controls correctly recognized and read aloud
essentially all these simple and compound characters. One subject
made no mistake at all, and one subject made a single mistake,
(/yu 4/ jade) (presented in the RFF) as
(/wang
misreading
2/king).
Experiment 3. In this experiment, we attempted to provide a
complementary test independent of reading for the two theories on
cortical representation of foveal vision. As shown in Table 1, in the
task of gender judgment of chimeric faces, the patient made
gender decisions mostly on the basis of the left half faces in the LFF
(17/20), whereas only 3/20 was based on the right half faces in the
RFF(x2(1) = 19.6, p = 0.000). Importantly, he was fairly confidence
about his judgments in all 20 chimeric faces (high confidence: 6,
modest confidence: 14, no confidence: 0), i.e., he was virtually not
aware that the faces were chimeric (see Figure 4A, lower panel).
In contrast, the two normal controls were aware that all face
stimuli were made of two half faces of opposite genders.

As clearly shown in Figure 6 (upper, C), when Chinese
characters were presented in the RFF but not the LFF, a region
in the left lateral mid-fusiform cortex was significantly activated(P#0.05, FDR-corrected). This region (Talairach Coordination: peak voxel: x = 238, y = 265, z = 21; extent: x =
235,247; y = 256,268; z = 219,3; Cluster: 45 voxels)
corresponds precisely to the location of the VWFA in the literature
[63,77].
Interestingly, there is some evidence for bilateral activation(P#0.05, FDR-corrected) in the early visual cortex from
stimuli presented in the LFF (Figure 6, lower, green and red arrow,
Talairach Coordination: x = 14, y = 271, z = 21, Cluster: 9
voxels; x = 26, y = 283, z = 18, Cluster: 7 voxels; x = 223, y =
271, z = 210, Cluster: 13 voxels), however the stimuli in the RFF
only activated the left early visual cortex (Figure 6, upper, green
arrow, Talairach Coordination: x = 211, y = 283, z = 210,
Cluster: 18 voxels; x = 226, y = 283, z = 210, Cluster: 32 voxels).

Discussion
The main goal of this study was to assess the two hotly debated
theories, the BPT and SFT, in a unique patient with splenium
lesion, by the combined use of neuropsychological tests and
multimodal imaging techniques (including T1/T2 weighted
structural MRIs, fMRI, and DTI).
Throughout our study, we have carefully considered the
following three critical methodology issues (see [29,30,35,54,81]
for detailed discussion). First, inter-hemispheric information
transfer and inhibition should be avoided or controlled for.
Accordingly, in the current study, we recruited a unique patient
with a splenium lesion, which was confirmed by multimodal
MRIs, particularly the DTI analysis. Second, the stimuli should be
presented precisely within the foveal field even in the half foveal
field. In this study, all stimuli, including reading materials and
chimeric faces, were presented within the foveal field. In addition,
as discussed in the Introduction, the visual features of Chinese
characters allow us to present them more easily, relative to
alphabetic words, within the foveal field. Third, more than one

fMRI results
Overall, Chinese characters activated a distributed network,
involving bilateral dorsolateral prefrontal, medial frontal, and
cingulate cortices, whereas additional activations were found in the
left fusiform, parietal gyri, under the RFF presentation condition.

Figure 6. fMRI activation maps for two presentation conditions in the patient. Upper: Characters presented in the RFF, Lower: Characters
presented in the LFF. The VWFA in the left lateral mid-fusiform cortex was activated when Chinese characters were presented in the RFF(C, the green
crosshair) but not in the LFF (G, the green crosshair). The Characters in the RFF activated only the left early visual cortices (green arrow in B, C, and D).
However, both the right (green arrow in G, H) and left early visual cortices (red arrow in E-H, at the same axial level as A-D respectively) were activated
when the Characters were presented in the LFF.
doi:10.1371/journal.pone.0023997.g006

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Foveal Splitting in a Splenium Lesioned Patient

medial to the VWFA [72,82–83], our detailed lesion analysis
revealed that the patient’s left FFA might be damaged while his
VWFA remained intact. Therefore, his facial gender judgment
was likely dependent on the (right) FFA, which is consistent with
the observation that the patient was not aware at all that the faces
he was viewing were chimeric.
More direct evidence for SFT comes from our fMRI experiment. As shown in Figure 6, the Chinese characters presented in
the RFF significantly activated the left lateral mid-fusiform gyrus
(upper, c, the green crosshair), but those presented in the LFF did
not. The left lateral mid-fusiform gyrus, i.e., VWFA, has been well
documented as a critical locus for visual word processing
[63,65,77,83–86]. Our fMRI results are consistent with those of
Cohen and colleagues’ studies in splenium lesion patients [63,64].
However, in these two studies, written words were presented in
eccentricities of 4.9u [63] and 2u–6u [64] respectively, well beyond
the foveal field, thus their results could not be used to address the
issue related to SFT and BPT, whereas our stimuli were presented
completely within the foveal field (#1.5u).
Thus, both behavioral and fMRI results we discussed so far are
in favor of the SFT but against the BPT.
However, our fMRI data also showed activation in both sides of
the early visual cortices when the stimulus was presented in the
LFF. This finding could be considered as evidence for the BPT,
which is also consistent with results of a large number of previous
studies [1–18,81,87]. For example, Bunt et al. [3] provided
anatomical evidence for bilateral foveal projections in the monkey,
although there were only about 7% (1/14) ganglion cells
projecting to opposite dLGN (dorsal lateral geniculate nucleus).
Frendich et al. [13] demonstrated behavioral evidence for double,
although weak, projections in a callosotomy patient. Vitctor et al.
[87] and Magni et al. [88] observed bilateral cortical representations of the foveal information, both using visual evoked
potentials. Kraft et al., [21] found bilateral activations in early
visual areas (V1–V3/Vp) when the stimuli (e.g., checkerboards or
colored objects, subtending 1.4u of visual angle) were presented 1.2
degree of visual angle right or left from the vertical meridian.
Therefore, based on the above finding, a clear picture emerges
regarding the cortical representation of fovea vision. We believe
that the foveal region does have bilateral projection to the early
visual cortex, much more robust contralaterally than ipsilaterally,
this account for the foveal sparing as well as other evidence that
supports BPT. However, although the ipsilateral projection may
show in fMRI studies of early visual cortex, and in perimetry
measures of simple visual detection, at object processing levels, our
study show that the representation of foveal stimuli is functionally
effectively split. This account accommodates the key evidence for
BFT, yet the fundamental conclusion is that foveal vision is
functionally split, which agrees with the SFT and is consistent with
a large number of behavioral studies involving object processing,
including reading and object naming [24–48].
In conclusion, the present study investigated a unique patient
with lesions in the splenium of the corpus callosum and the left
medial occipitotemporal region, through a series of neuropsychological tests and multimodal MRI scans. Results of the current
study, together with existing evidence in the literature, suggest that
the representation of foveal stimuli, although likely bilaterally
projected in early visual cortices, is effectively functionally split at
object processing levels.

type of visual materials should be used, ideally with the combined
use of behavioral and biological methods. We thus adopted not
only a series of reading tasks but also a face recognition task.
Although several authors have pointed out the importance of face
stimuli in understanding the nature of foveal representation
[30,35], to our knowledge, no such a study has yet been reported.
Importantly, our fMRI experiment revealed the physiological
manifestations of visual perception at both higher and lower levels
in the same individual, showing a more comprehensive picture of
foveal representation.
Results of the three behavioral experiments and fMRI
activation in the VWFA only from RFF stimulation provide
converging support for the SFT, although the bilateral activations
of the early visual cortices under the LFF presentation conditions
seems to be consistent with the BPT. We next discuss these
seemingly conflicting findings together with the relevant results of
the literature.
Behavioral experiment 1 demonstrated that the patient had
difficulties in recognizing reading materials presented in the foveal
region but left to the fixation. Specifically, when the left-right
structured compound Chinese characters were presented briefly in
the central foveal field, he could correctly read only 14 out of the
60 characters tested. Critically, his reading errors were mainly
resulted from the failure of recognizing the left components of
these compound characters, in that he could recognize the right
components of 73% characters tested but the left component only
23% of characters tested. The patient’s above reading problems is
unlikely caused by his attentional bias to the right components (see
Note 1), because he made virtually the same number of errors in
reading both types of the characters.
Another possible interpretation was his neglect of the left
components, particularly when left and right components were
simultaneously presented in the LFF and RFF. However, this
interpretation is inconsistent with the fact that for the characters
the patient misread, he misread rather than omitted the left
components. Specifically, among the 38 characters he misread, in
only 2 of them the left component was omitted (he read instead the
character with the name of the right component), whereas in 26 of
the misread characters, the left components were substituted by
different components.
The possibility of neglect is further ruled out by the patient’s
performance in the two neglect tests and behavioral Experiment 2.
His performances were normal in the line bisection test [74] and
the cancellation task [75], the two most commonly used clinical
tests for neglect. In behavioral Experiment 2, the whole characters
were randomly presented in the LFF or RFF (thus no extinction),
and the patient was asked to read them aloud. When the stimuli
were presented in the LFF, he read correctly 8 of 18 simple
characters and none of 64 compound characters. When the stimuli
were presented in the RFF, however, his reading performance was
reasonably good: he correctly read 17 of 18 simple characters and
33 of 64 compound characters.
The behavioral Experiment 3, which did not involve reading,
adds another piece of evidence for the SFT. In this experiment, the
patient was asked to perform a facial gender decision task, in
which the chimeric face (half female face and half male face) was
presented strictly within the foveal field. As Table 1 clearly shows,
his judgment for the gender of the chimeric was virtually (17 out of
20) exclusively based on the left half-face while ignoring the right
half-face. This result is well in accordance with the SFT. First, the
patient’s right fusiform was intact and numerous studies have
demonstrated a right hemispheric dominance for processing face
information [66–71]. Second, although some studies suggest that
in the left fusiform there is a face processing area (the left FFA),

PLoS ONE | www.plosone.org

Author Contributions
Conceived and designed the experiments: BL CS XW. Performed the
experiments: BL RZ. Analyzed the data: CS XW SH. Wrote the paper: CS
XW SH.

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Foveal Splitting in a Splenium Lesioned Patient

References
31. Van der Haegen L, Drieghe D, Brysbaert M (2010) The Split Fovea Theory and
the Leicester critique: What do the data say? Neuropsychologia 48: 96–106.
32. Lavidor M, Ellis AW, Shillcock R, Bland T (2001) Evaluating a split processing
model of visual word recognition: effects of word length. Cogn Brain Res 12:
265–272.
33. Ellis AW (2004) Length, formats, neighbours, hemispheres, and the processing of
words presented laterally or at fixation. Brain Lang 88: 355–366.
34. Lavidor M, Walsh V (2003) A magnetic stimulation examination of orthographic
neighborhood effects in visual word recognition. J Cogn Neurosci 15: 354–363.
35. Lavidor M, Walsh V (2004) Opinion - The nature of foveal representation. Nat
Rev Neurosci 5: 729–735.
36. Lavidor M, Walsh V (2004) Magnetic stimulation studies of foveal representation. Brain Lang 88: 331–338.
37. Lavidor M, Whitney C (2005) Word length effects in Hebrew. Cogn Brain Res
24: 127–132.
38. Shillcock R, Ellison TM, Monaghan P (2000) Eye-fixation behavior, lexical
storage, and visual word recognition in a split processing model. Psychol Rev
107: 824–851.
39. Shillcock RC, McDonald SA (2005) Hemispheric division of labour in reading.
J Res Read 28: 244–257.
40. Hsiao JHW, Shillcock R (2005) Foveal splitting causes differential processing of
Chinese orthography in the male and female brain. Cogn Brain Res 25:
531–536.
41. Hsiao JHW, Shillcock R, Lavidor M (2007) An examination of semantic radical
combinability effects with lateralized cues in Chinese character recognition.
Percept Psychophys 69: 338–344.
42. Hsiao JHW, Shillcock R, Lavidor M (2006) A TMS examination of semantic
radical combinability effects in Chinese character recognition. Brain Res 1078:
159–167.
43. Skarratt PA, Lavidor M (2006) Magnetic stimulation of the left visual cortex
impairs expert word recognition. J Cogn Neurosci 18: 1749–1758.
44. Martin CD, Thierry G, Demonet JF, Roberts M, Nazir T (2007) ERP evidence
for the split fovea theory. Brain Res 1185: 212–220.
45. Whitney C, Lavidor M (2004) Why word length only matters in the left visual
field. Neuropsychologia 42: 1680–1688.
46. Whitney C, Lavidor M (2005) Facilitative orthographic neighborhood effects:
The SERIOL model account. Cogn Psychol 51: 179–213.
47. Van der Haegen L, Brysbaert M, Davis CJ (2009) How does interhemispheric
communication in visual word recognition work? Deciding between early and
late integration accounts of the split fovea theory. Brain Lang 108: 112–121.
48. Hunter ZR, Brysbaert M, Knecht S (2007) Foveal word reading requires
interhemispheric communication. J Cogn Neurosci 19: 1373–1387.
49. Ellis AW, Brooks J, Lavidor M (2005) Evaluating a split fovea model of visual
word recognition: effects of case alternation in the two visual fields and in the left
and right halves of words presented at the fovea. Neuropsychologia 43:
1128–1137.
50. Whitney C (2001) How the brain encodes the order of letters in a printed word:
The SERIOL model and selective literature review. Psychon Bull Rev 8:
221–243.
51. Van der Haegen L, Brysbaert M (2010) The mechanisms underlying the
interhemispheric integration of information in foveal word recognition: Evidence
for transcortical inhibition. Brain Lang, In press.
52. Cook ND (1984) Homotopic callosal inhibition. Brain Lang 23: 116–125.
53. Cook ND (1984) Callosal inhibition: the key to the brain code. Behav Sci 29:
98–110.
54. Bloom JS, Hynd GW (2005) The role of the corpus callosum in interhemispheric
transfer of information: excitation or inhibition? Neuropsychol Rev 15: 59–71.
55. Marzi CA, Bisiacchi P, Nicoletti R (1991) Is Interhemispheric-Transfer of
Visuomotor Information Asymmetric - Evidence from a Metaanalysis.
Neuropsychologia 29: 1163–1177.
56. Westerhausen R, Kreuder F, Woerner W, Huster RJ, Smit CM, et al. (2006)
Interhemispheric transfer time and structural properties of the corpus callosum.
Neurosci Lett 409: 140–145.
57. Zaidel E, Iacoboni M (2003) Introduction: Poffenberger’s simple reaction time
paradigm for measuring interhemispheric transfer time. In: Zaidel E,
Iacoboni M, eds. The Parallel Brain: The Cognitive Neuroscience of the
Corpus Callosum. Cambridge: MIT Press. pp 1–8.
58. Saron CD, Foxe JJ, Simpson GV, Vaughan HG (2003) Interhemispheric
visuomotor activation: spatiotemporal electrophysiology related to reaction time.
In: Zaidel E, Iacoboni M, eds. The Parallel Brain: The Cognitive Neuroscience
of the Corpus Callosum. Cambridge: MIT Press. pp 171–219.
59. Siéroff E, Lavidor M (2007) Examination of the split fovea theory in a case of
pure left hemialexia. Cognitive Neuropsychology, 24: 243–259.
60. Li Y, Kang JS (1993) Analysis of phonetics of the ideophonetic characters in
Modern Chinese. In: Chen Y, ed. Information analysis of usage of characters in
modern Chinese. Shanghai: Shanghai Education Publisher. pp 84–98.
61. Wang N (1997) The structure and meaning of Chinese characters and words. In:
Peng DL, ed. Research of Chinese Cognition. Jinan: Shandong Education Press.
pp 35–64.
62. Wang N, Zhou XL (1999) Chinese character. Hong Kong: Hoi Fung Publisher.
63. Cohen L, Dehaene S, Naccache L, Lehericy S, Dehaene-Lambertz G, et al.
(2000) The visual word form area: spatial and temporal characterization of an

1. Tootell RB, Switkes E, Silverman MS, Hamilton SL (1988) Functional anatomy
of macaque striate cortex. II. Retinotopic organization. J Neurosci 8:
1531–1568.
2. Stone J, Leicester J, Sherman SM (1973) The naso-temporal division of the
monkey’s retina. J Comp Neurol 150: 333–348.
3. Bunt AH, Minckler DS, Johanson GW (1977) Demonstration of Bilateral
Projection of Central Retina of Monkey with Horseradish-Peroxidase Neuronography. J Comp Neurol 171: 619–630.
4. Leventhal AG, Ault SJ, Vitek DJ (1988) The Nasotemporal Division in Primate
Retina - the Neural Bases of Macular Sparing and Splitting. Science 240: 66–67.
5. Fukuda Y, Sawai H, Watanabe M, Wakakuwa K, Morigiwa K (1989)
Nasotemporal overlap of crossed and uncrossed retinal ganglion cell projections
in the Japanese monkey (Macaca fuscata). J Neurosci 9: 2353–2373.
6. Chalupa LM, Lia B (1991) The Nasotemporal Division of Retinal GanglionCells with Crossed and Uncrossed Projections in the Fetal Rhesus-Monkey.
J Neurosci 11: 191–202.
7. Stone J (1966) The naso-temporal division of the cat’s retina. J Comp Neurol
126: 585–600.
8. Trauzettel-Klosinski S, Reinhard J (1998) The vertical field border in
hemianopia and its significance for fixation and reading. Invest Ophthalmol
Vis Sci 39: 2177–2186.
9. Huber A (1962) Homonymous Hemianopia after Occipital Lobectomy.
Am J Ophthalmol 54: 623–629.
10. Bunt AH, Minckler DS (1977) Foveal Sparing - New Anatomical Evidence for
Bilateral Representation of Central Retina. Arch Ophthalmol 95: 1445–1447.
11. Sugishita M, Hemmi I, Sakuma I, Beppu H, Shiokawa Y (1993) The problem of
macular sparing after unilateral occipital lesions. J Neurol 241: 1–9.
12. Reinhard J, Trauzettel-Klosinski S (2003) Nasotemporal overlap humans: A
functional of retinal ganglion cells in study. Invest Ophthalmol Vis Sci 44:
1568–1572.
13. Fendrich R, Wessinger CM, Gazzaniga MS (1996) Nasotemporal overlap at the
retinal vertical meridian: Investigations with a callosotomy patient. Neuropsychologia 34: 637–646.
14. Gazzaniga MS (2000) Cerebral specialization and interhemispheric communication - Does the corpus callosum enable the human condition? Brain 123:
1293–1326.
15. Marzi CA, Mancini F, Sperandio I, Savazzi S (2009) Evidence of midline retinal
nasotemporal overlap in healthy humans: A model for foveal sparing in
hemianopia? Neuropsychologia 47: 3007–3011.
16. Jordan TR, Paterson KB, Stachurski M (2008) Re-Evaluating Split-Fovea
Processing in Word Recognition: Effects of Retinal Eccentricity on Hemispheric
Dominance. Neuropsychology 22: 738–745.
17. Jordan TR, Paterson KB, Stachurski M (2009) Re-evaluating split-fovea
processing in word recognition: Effects of word length. Cortex 45: 495–505.
18. Jordan TR, Paterson KB, Kurtev S (2009) Reevaluating split-fovea processing in
word recognition: Hemispheric dominance, retinal location, and the wordnonword effect. Cogn Affect Behav Ne 9: 113–121.
19. Jordan TR, Paterson KB, Kurtev S, Xu MY (2010) Re-evaluating split-fovea
processing in word recognition: Effects of word length during monocular
viewing. Cortex 46: 100–105.
20. Jordan TR, Paterson KB, Kurtev S, Xu MY (2010) Re-evaluating split-fovea
processing in word recognition: Effects of fixation location within words. Cortex
46: 298–309.
21. Kraft A, Schira MM, Hagendorf H, Schmidt S, Olma M, et al. (2005) FMRI
localizer technique: Efficient acquisition and functional properties of single
retinotopic positions in the human visual cortex. Neuroimage 28: 453–463.
22. Brandt T, Stephan T, Bense S, Yousry TA, Dieterich M (2000) Hemifield visual
motion stimulation: An example of interhemispheric crosstalk. Neuroreport 11:
2803–2809.
23. Tootell RBH, Mendola JD, Hadjikhani NK, Liu AK, Dale AM (1998) The
representation of the ipsilateral visual field in human cerebral cortex.
Proceedings of the National Academy of Sciences of the United States of
America 95: 818–824.
24. Brysbaert M (1994) Interhemispheric transfer and the processing of foveally
presented stimuli. Behav Brain Res 64: 151–161.
25. Brysbaert M, Vitu F, Schroyens W (1996) The right visual field advantage and
the optimal viewing position effect: On the relation between foveal and
parafoveal word recognition. Neuropsychology 10: 385–395.
26. Brysbaert M (2004) The importance of interhemispheric transfer for foveal
vision: a factor that has been overlooked in theories of visual word recognition
and object perception. Brain Lang 88: 259–267.
27. Lavidor M, Hayes A, Shillcock R, Ellis AW (2004) Evaluating a split processing
model of visual word recognition: Effects of orthographic neighborhood size.
Brain Lang 88: 312–320.
28. Lindell AK, Nicholls MER (2003) Cortical representation of the fovea:
Implications for visual half-field research. Cortex 39: 111–117.
29. Ellis AW, Brysbaert M (2010) Split fovea theory and the role of the two cerebral
hemispheres in reading: A review of the evidence. Neuropsychologia 48:
353–365.
30. Ellis A, Brysbaert M (2010) Divided opinions on the split fovea. Neuropsychologia 48: 2784–2785.

PLoS ONE | www.plosone.org

9

August 2011 | Volume 6 | Issue 8 | e23997

Foveal Splitting in a Splenium Lesioned Patient

64.

65.
66.
67.

68.

69.

70.
71.

72.

73.
74.
75.
76.

initial stage of reading in normal subjects and posterior split-brain patients. Brain
123: 291–307.
Molko N, Cohen L, Mangin JF, Chochon F, Lehericy S, et al. (2002) Visualizing
the neural bases of a disconnection syndrome with diffusion tensor imaging.
J Cogn Neurosci 14: 629–636.
McCandliss BD, Cohen L, Dehaene S (2003) The visual word form area:
expertise for reading in the fusiform gyrus. Trends Cogn Sci 7: 293–299.
Levy J, Sperry RW, Trevarth C (1972) Perception of Bilateral Chimeric Figures
Following Hemispheric Deconnection. Brain 95: 61–78.
Luh KE, Redl J, Levy J (1994) Left-Handers and Right-Handers See People
Differently - Free-Vision Perceptual Asymmetries for Chimeric Stimuli. Brain
Cogn 25: 141–160.
Burt DM, Perrett DI (1997) Perceptual asymmetries in judgements of facial
attractiveness, age, gender, speech and expression. Neuropsychologia 35:
685–693.
Kanwisher N, McDermott J, Chun MM (1997) The fusiform face area: A
module in human extrastriate cortex specialized for face perception. J Neurosci
17: 4302–4311.
Haxby JV, Hoffman EA, Gobbini MI (2000) The distributed human neural
system for face perception. Trends Cogn Sci 4: 223–233.
Yovel G, Tambini A, Brandman T (2008) The asymmetry of the fusiform face
area is a stable individual characteristic that underlies the left-visual-field
superiority for faces. Neuropsychologia 46: 3061–3068.
Puce A, Allison T, Asgari M, Gore JC, McCarthy G (1996) Differential
sensitivity of human visual cortex to faces, letterstrings, and textures: A
functional magnetic resonance imaging study. J Neurosci 16: 5205–5215.
Binder JR, Lazar RM, Tatemichi TK, Mohr JP, Desmond DW, et al. (1992)
Left hemiparalexia. Neurology 42: 562–569.
Schenkenberg T, Bradford DC, Ajax ET (1980) Line Bisection and Unilateral
Visual Neglect in Patients with Neurologic Impairment. Neurology 30: 509–517.
Albert ML (1973) A simple test of visual neglect. Neurology 23: 658–664.
Hofer S, Frahm J (2006) Topography of the human corpus callosum revisited Comprehensive fiber tractography using diffusion tensor magnetic resonance
imaging. Neuroimage 32: 989–994.

PLoS ONE | www.plosone.org

77. Cohen L, Lehericy S, Chochon F, Lemer C, Rivaud S, et al. (2002) Languagespecific tuning of visual cortex functional properties of the Visual Word Form
Area. Brain 125: 1054–1069.
78. Cox RW (1996) AFNI: software for analysis and visualization of functional
magnetic resonance neuroimages. Comput Biomed Res 29: 162–173.
79. Talairach J, Tournoux P (1988) Co-Planar Stereotaxic Atlas of the Human
Brain: 3-D Proportional System: An Approach to Cerebral Imaging. New York:
Thieme Medical Publishers.
80. Cohen L, Martinaud O, Lemer C, Lehericy S, Samson Y, et al. (2003) Visual
word recognition in the left and right hemispheres: Anatomical and functional
correlates of peripheral alexias. Cereb Cortex 13: 1313–1333.
81. Jordan TR, Paterson KB (2009) Re-evaluating split-fovea processing in word
recognition: A critical assessment of recent research. Neuropsychologia 47:
2341–2353.
82. Hasson U, Levy I, Behrmann M, Hendler T, Malach R (2002) Eccentricity bias
as an organizing principle for human high-order object areas. Neuron 34:
479–490.
83. Gaillard R, Naccache L, Pinel P, Clemenceau S, Volle E, et al. (2006) Direct
intracranial, FMRI, and lesion evidence for the causal role of left inferotemporal
cortex in reading. Neuron 50: 191–204.
84. Cohen L, Dehaene S (2004) Specialization within the ventral stream: the case for
the visual word form area. Neuroimage 22: 466–476.
85. Baker CI, Liu J, Wald LL, Kwong KK, Benner T, et al. (2007) Visual word
processing and experiential origins of functional selectivity in human extrastriate
cortex. Proc Natl Acad Sci U S A 104: 9087–9092.
86. Starrfelt R, Gerlach C (2007) The visual what for area: Words and pictures in
the left fusiform gyrus. Neuroimage 35: 334–342.
87. Victor JD, Conte MM, Iadecola C (1991) Ocular Dependence of Hemifield
Visual Evoked-Potentials - Relevance to Bilateral Cortical Representation of
Central Vision. Clin Vision Sci 6: 261–276.
88. Magni R, Reni G, Rinaldi G, Ravalico G, Brancato R (1996) Homonymous
bilateral hemianopsia: electrophysiological study of a case. Eur J Ophthalmol 6:
63–68.

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August 2011 | Volume 6 | Issue 8 | e23997