title: The roles of the "visual word form area" in reading.
abstract: Activation of the left midfusiform gyrus in response to reading words and pseudowords is such a reliable finding in functional imaging that this region has been called "the visual word form area" (VWFA). However, this label has recently been challenged, because activation in VWFA is also observed in other lexical tasks. We evaluated whether VWFA is necessary, sufficient, or specialized for reading by examining how frequently acute lesions in VWFA disrupt tasks that require access to written word forms versus other lexical tasks. We administered lexical tasks with spoken and written input and output, and identified damage or dysfunction of VWFA and other regions of interest (ROI) on diffusion- and perfusion-weighted imaging (DWI and PWI) in 80 patients within 24 h of onset of acute left ischemic stroke. Associations between abnormalities in each region of interest and impairment on lexical tasks were evaluated with chi-squared tests. Damage or dysfunction of VWFA was not significantly associated with impairment of written word comprehension or lexical decision, but was significantly associated with impairment on all tasks requiring lexical output: oral reading and oral naming (visual or tactile input), and written naming. We account for these results and results from functional imaging by proposing that the left midfusiform gyrus normally has two roles in reading: (1) computation of location- and modality-independent grapheme sequences from written word stimuli, and (2) a modality-independent stage of lexical processing that links modality-specific input and output representations. VWFA is not necessary for the former because the right homologue of VWFA can immediately assume this role.
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. argye@JHMI@edu
authors.forename: Argye E
authors.initials: AE
authors.lastname: Hillis
authors.forename: Melissa
authors.initials: M
authors.lastname: Newhart
authors.forename: Jennifer
authors.initials: J
authors.lastname: Heidler
authors.forename: Peter
authors.initials: P
authors.lastname: Barker
authors.forename: Edward
authors.initials: E
authors.lastname: Herskovits
authors.forename: Mahaveer
authors.initials: M
authors.lastname: Degaonkar
mesh_terms: D000328:Adult; D002545:Brain Ischemia / Q000503:physiopathology / Q000523:psychology*; D001931:Brain Mapping / Q000379:methods; D007839:Functional Laterality; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D010775:Photic Stimulation; D011932:Reading; D013997:Time Factors; D014110:Touch; D014796:Visual Perception / Q000502:physiology*