Faces and word forms can co-exist in right ventro-occipital temporal cortex – evidence from left-hemisphere perinatal stroke

In most healthy adult humans, the right ventro-occipital temporal cortex (vOTC) is more involved in face perception than its left-hemisphere counterpart. Several hypotheses link this right-lateralization for face processing to left-lateralization of language and visual word form processing. In its strongest form, this account assumes an encroachment by word form processing into left vOTC territory that would otherwise be dedicated to face processing, causing face processing that would otherwise be bilateral to rely relatively more on right vOTC. By this logic, if visual word recognition came to rely predominantly on the right hemisphere, face processing should become left-lateralized. Alternatively, it would have to share neural territory with words in right vOTC, which might negatively impact behavioral performance due to crowding. Here we used functional MRI and the Cambridge Face Memory Test in fifteen male and female adolescents and young adults with a history of left hemisphere perinatal stroke who are right-lateralized for language and word form processing and whose vOTC is anatomically and functionally intact in both hemispheres. Comparison with fourteen neurotypical controls revealed no significant group differences in strength or lateralization of face activation, and no significant differences in face recognition. These results demonstrate that after left-hemisphere perinatal stroke, face and word form processing can both be right-lateralized without significant detriment to either. This is reminiscent of the observation that emotional prosody and sentence processing – typically lateralized to the right and left hemisphere, respectively – are both successfully supported by the right hemisphere in the same participant group. Significance Statement This study informs our understanding of the causes and consequences of lateralization for visual object processing in ventro-occipitotemporal cortex (vOTC) by demonstrating that after a large perinatal stroke to the left hemisphere, faces and words can share right vOTC territory without compromise of neural or behavioral outcomes. This suggests that the lateralization pattern typically observed in neurologically healthy adults (left-lateralization of word forms and right-lateralization of faces) is unlikely to be driven solely by competition for left vOTC territory. It highlights the influence of other factors, such as intrahemispheric connectivity and asymmetrical hemispheric processing preferences, in determining hemispheric lateralization for face processing.