Right-Lateralization of the Visual Word Form Area after Left-Hemisphere Perinatal Stroke

In literate adults, an area along the left posterior fusiform gyrus that is often referred to as the "visual word form area" (VWFA) responds particularly strongly to written characters compared with other visually similar stimuli. Theoretical accounts differ in whether they attribute the strong left-lateralization of the VWFA to a left-hemisphere (LH) bias toward visual features used in script, to competition of visual word form processing with that of other visual stimuli processed in the same general cortical territory (especially faces), or to the well established left-lateralization of the language system. Here we used functional magnetic resonance imaging to test the last hypothesis by investigating lateralization of the VWFA in participants (male and female) who have right-hemisphere language due to a large LH perinatal stroke. Demographically matched controls were included for comparison. All participants had intact language skills and were proficient readers; age at testing ranged from 9.75 years to early adulthood. Activation maps contrasting activation during rapid presentation of pseudowords and pictures of places revealed left-lateralized fusiform activation in controls, as expected. In participants with left-hemisphere perinatal stroke and right-lateralized language, the VWFA was instead found in the right fusiform gyrus, despite the fact that the left-hemisphere tissue normally occupied by the VWFA was intact and responded normally to pictures of places. Region-of-interest analyses confirmed right-lateralization for visual word form processing, both relative to place stimuli and relative to a resting baseline. This provides compelling evidence that the lateralization of the VWFA indeed follows that of the frontotemporal language system.