What and where in mirror reading

Abstract

In a combined voxel-based morphometry and functional magnetic resonance imaging study on the practice of mirror reading, we recently found a shift of activation from right superior parietal to right dorsal occipital cortex and a corresponding increase of gray matter. We interpreted this shift of activation and the corresponding structural changes as a shift from effortful visuospatial transformation to a more direct processing of mirrored words (Ilg et al., 2008). To test this hypothesis, we now analyzed brain activation patterns associated with different aspects of mirror reading. Activation at the dorsal occipital cortex and bilateral parietal cortex (dorsal visual stream) was related to inverse text processing, whereas activation of areas at the inferior and ventral occipitotemporal cortex (ventral visual stream) was associated with decoding of mirrored words. This indicates that the dichotomy of content-related ("what") and process-related ("where") higher visual functions also applies to mirror reading.