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Anatomy of the Visual Word Form Area in Dyslexia

Jamie L. MitchelliD, Maya YablonskiiD, Mia JimeneziD, Howard ChiuiD, Jason D. YeatmaniD

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Abstract

The Visual Word Form Area (VWFA), located in ventral occipitotemporal cortex, plays a critical role in skilled reading. Researchers have theorized that the VWFA develops in its specific anatomical location due to the convergence of major white matter tracts and proximity to functionally similar regions. This suggests that precise anatomical positioning may be crucial for optimal VWFA function. Previous research has identified several functional differences in this region between typical and struggling readers (i.e. dyslexia): struggling readers show weaker text-selective responses and often exhibit a smaller or even absent VWFA. However, it remains unexplored whether the precise anatomical location of this region also differs between typical and struggling readers. We tested whether VWFA anatomy differs between children with and without dyslexia (N=87). Participants completed a functional localizer, which we used to manually define the VWFA in each individual's native anatomy. We examined whether: (1) VWFA anatomical location relates to reading ability, (2) children with dyslexia show greater variability in VWFA location compared to typical readers, and (3) VWFA location with respect to white matter tracts relates to reading ability. Results reveal that, despite being smaller in children with dyslexia, there is no relationship between VWFA location and reading ability. Specifically, individual VWFA location relative to anatomy, relative to other's VWFAs, and relative to white matter tracts, is not related to reading ability. These findings suggest that while the VWFA's general anatomy may be facilitated by development, its precise location remains stable and unrelated to reading proficiency.

In-depth summary

Claude Opus 5.5 · xhigh effort · 8 Nov 2026 · from the full text of version 2 (17 Sept 2026) · CC BY 4.0

In 84 children, the Visual Word Form Area (VWFA) was smaller in dyslexia, but its cortical position, between-child spread and white matter tract overlap were unrelated to reading skill.

Struggling readers are reported to have smaller, less text-selective (sometimes absent) VWFAs, and the region's site in ventral occipitotemporal cortex is theorized to follow from the convergence of major white matter tracts there. The authors say it was unexplored whether its precise location also differs in dyslexia; this work tests location, consistency across children and tract overlap against reading skill.

Key results

  1. SuggestedThe center of each child's VWFA-1 and VWFA-2 in MNI coordinates did not differ between dyslexic and typical readers and did not correlate with reading scores. VWFA-2 sat more laterally in dyslexia at a nominal threshold, but this did not survive Bonferroni correction.

    VWFA-1 x, y, z group tests: p = 0.3625, 0.6654, 0.8665 (bf01 2.627, 3.455, 3.695). VWFA-2 y, z: p = 0.3488, 0.1273 (bf01 2.509, 1.355). VWFA-2 x: t(39.20) = -2.308, p = 0.0264, bf01 = 0.422; Bonferroni-corrected p = 0.158. Pearson correlations with WJ BRS: all p > 0.3, bf01 > 4, except VWFA-2 x (p = 0.071, bf01 = 1.223). · 3.2 VWFA Location is Unrelated to Reading…; Figure legends

  2. SuggestedChildren with dyslexia did not have a more scattered VWFA location. Distances from each child's VWFA center to the group center were similar in both groups and did not relate to reading scores.

    Spread, dyslexia vs typical (Welch): VWFA-1 t(42.85) = 0.245, p = 0.808, bf01 = 3.647; VWFA-2 t(45.99) = -0.109, p = 0.913, bf01 = 3.616. Distance to the all-participant center vs WJ BRS: VWFA-1 r = -0.039, p = 0.768, bf01 = 6.00; VWFA-2 r = 0.137, p = 0.315, bf01 = 3.67. · 3.3 Between-Participant Variability in VWFA…; Figure legends

  3. SuggestedWithin each VWFA, average streamline density did not differ by group or correlate with reading scores for any of six reading-related tracts: arcuate (Arc), posterior arcuate (pArc), inferior fronto-occipital (IFOF), inferior longitudinal (ILF), and anterior and posterior vertical occipital (aVOF, pVOF) fasciculi.

    Tracts were segmented with pyAFQ 3.3 from QSIprep tractograms, and density maps were projected to the native surface. Welch tests on mean streamlines per vertex: no bundle differed in either VWFA (p > 0.1, bf01 > 1.5; Supplementary Table S2). Pearson correlations with WJ BRS: none significant (p > 0.3; Supplementary Table S3). · 2.4.1 Fiber Tractography; 3.4 Structural Connectivity of VWFA is Unrelated…

  4. ShownRe-measured as cortical surface area, both VWFAs were much smaller in children with dyslexia than in typical readers. This confirms the authors' earlier report on the same functional data.

    VWFA-1: 27.213 mm^2 (sd 48.261) in dyslexia vs 89.580 mm^2 (sd 95.042) in typical readers, d = -0.946. VWFA-2: 29.312 mm^2 (sd 42.035) vs 148.640 mm^2 (sd 152.810), d = -1.324. The authors describe this as roughly 30% and 20% of typical size. Figure 1 n = 24 typical, 60 dyslexia. · 3.1 VWFA Size is Related to Reading Ability; Figure legends

  5. SuggestedThe two VWFAs overlapped different tracts. VWFA-1 intersected the ILF and VOF, while VWFA-2 showed greater connectivity with the Arc.

    This is a descriptive comparison of mean streamline density per tract within each ROI (Figure 3c), which the authors call the expected pattern and consistent with earlier work. No formal statistical test of the VWFA-1 vs VWFA-2 contrast is reported. · 3.4 Structural Connectivity of VWFA is Unrelated…; Figure legends

Methods, data and reproducibility

VWFA-1 and VWFA-2 were hand-drawn on each child's native surface from an fMRI localizer, projected to fsaverage and reduced to a center vertex. Center coordinates, distance to group centers and pyAFQ streamline density of six tracts inside each VWFA were compared between groups (Welch t-tests) and correlated with Woodcock-Johnson Basic Reading Skills (WJ BRS) scores, with Bayes factors for nulls.

  • Children aged 7-13, screened into struggling readers (dyslexia) and typical readers; 3 excluded because of high motion in functional data · human (children) · n = 87 enrolled (63 dyslexia, 24 typical); 84 analyzed
  • fMRI functional localizer (multiband gradient EPI, TR 1.19 s, TE 30 ms, 2.4 mm isotropic), previously reported by the authors · human
  • Multi-shell diffusion MRI: 180 diffusion-weighted volumes (b = 1000/2000/3000 s/mm2 with 30/60/90 directions) plus 14 b = 0 volumes, 1.5 mm isotropic · human
  • Woodcock-Johnson Basic Reading Skills composite (Word Attack and Letter Word Identification subtests) · human
Methods & tools
QSIprep 0.22.0, Nipype 1.8.6, MRtrix3, Nilearn 0.10.1, Dipy 1.8.0, fMRIprep, FreeSurfer, pyAFQ 3.3, scipy.stats, numpy, Pingouin, Woodcock-Johnson Basic Reading Skills
Software & environment
QSIprep 0.22.0 (built on Nipype 1.8.6, using Nilearn 0.10.1 and Dipy 1.8.0), MRtrix3 and pyAFQ 3.3; fMRIprep and FreeSurfer versions are not given. Statistics were run in Python with scipy.stats, numpy and Pingouin. No container or requirements file is mentioned.
Reproducibility gaps
Released data are de-identified. Screening criteria, demographics (Supplementary Table S1), Supplementary Tables S2-S3, and fMRI acquisition and ROI-definition details are left to other papers or supplements not in this text. Several in-text citations are missing.
Limitations (3)
  • The authors caution that intervention studies could still uncover within-child anatomical changes in the VWFA that accompany improvements in reading. · stated by the authors
  • Null evidence is modest: 24 typical readers vs 60 to 63 with dyslexia. Exact bf01 for null location and spread tests span 1.223 to 6.00 (some correlations given only as > 4); the VWFA-2 x group test had bf01 = 0.422 and tract tests only bf01 > 1.5. Handling of tiny or absent VWFAs is not described. · noted in this summary
  • Internal inconsistencies: the dyslexia group is N=63 in Methods but n=60 in Figure 1; the tract analysis mentions six, then seven bundles; and its closing sentence calls location relative to tracts 'generally significantly related' to reading, contradicting the nulls. · noted in this summary

Read this if you work on the neurobiology of dyslexia or ventral temporal cortex organization and want individual-level tests of whether VWFA position, spread or tract overlap relate to reading skill.

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