title: Grapheme-colour synaesthetes show increased grey matter volumes of parietal and fusiform cortex.
abstract: In synaesthesia, stimulation of a sensory modality triggers abnormal additional perceptions. Voxel-based morphometry (VBM) was used in 18 grapheme-colour synaesthetes to investigate the neuro-anatomical basis of their abnormal perceptions. More specifically, we tested the hypothesis that in synaesthesia altered connectivity in temporo-occipital and parietal areas may be associated with grey matter (GM) changes. The data reveal increased GM volumes in fusiform and intraparietal cortices. These findings are consistent with the two-stage model of grapheme-colour synaesthesia implying cross-activation at the level of the fusiform gyrus (FG) and 'hyperbinding' at the level of the parietal cortex. The observed structural differences in grapheme-colour synaesthetes with abnormal additional perceptions may also shed some light on the neural bases of abnormal perceptions in neurological and psychiatric disorders.
authors.affiliation: Cognitive Neurology, Institute of Neuroscience and Biophysics-Medicine, Research Centre Jülich, Jülich, Germany. P.H.Weiss@fz-juelich.de
authors.forename: Peter H
authors.initials: PH
authors.lastname: Weiss
authors.forename: Gereon R
authors.initials: GR
authors.lastname: Fink
mesh_terms: D000328:Adult; D001244:Association; D001931:Brain Mapping / Q000379:methods; D003118:Color Perception / Q000502:physiology*; D006179:Gyrus Cinguli / Q000033:anatomy & histology*; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D010296:Parietal Lobe / Q000033:anatomy & histology*; D010700:Phonetics; D055815:Young Adult