title: Parieto-occipital suppression eliminates implicit bidirectionality in grapheme-colour synaesthesia.
abstract: Synaesthesia is a condition in which the input of one sensory modality triggers extraordinary additional experiences. On an explicit level, subjects affected by this condition normally report unidirectional experiences. In grapheme-colour synaesthesia for example, the letter A printed in black may trigger a red colour experience but not vice versa. However on an implicit level, at least for some types of synaesthesia, bidirectional activation is possible. In this study we tested whether bidirectional implicit activation is mediated by the same brain areas as explicit synaesthetic experiences. Specifically, we demonstrated suppression of implicit bidirectional activation with the application of transcranial magnetic stimulation over parieto-occipital brain areas. Our findings indicate that parieto-occipital regions are not only involved in explicit but also implicit synaesthetic binding.
authors.affiliation: University of Bern, Bern, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rothen
authors.forename: Thomas
authors.initials: T
authors.lastname: Nyffeler
authors.forename: Roman
authors.initials: R
authors.lastname: von Wartburg
authors.forename: René
authors.initials: R
authors.lastname: Müri
authors.forename: Beat
authors.initials: B
authors.lastname: Meier
mesh_terms: D000328:Adult; D003118:Color Perception / Q000502:physiology*; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006801:Humans; D008297:Male; D009778:Occipital Lobe / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012094:Repression, Psychology; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult