Article abstract

Nature Neuroscience 10, 792 - 797 (2007)
Published online: 21 May 2007 | doi:10.1038/nn1906

Increased structural connectivity in grapheme-color synesthesia

Romke Rouw1 & H Steven Scholte1

Diffusion tensor imaging allowed us to validate for the first time the hypothesis that hyperconnectivity causes the added sensations in synesthesia. Grapheme-color synesthetes (n = 18), who experience specific colors with particular letters or numbers (for example, 'R is sky blue'), showed greater anisotropic diffusion compared with matched controls. Greater anisotropic diffusion indicates more coherent white matter. Anisotropy furthermore differentiated subtypes of grapheme-color synesthesia. Greater connectivity in the inferior temporal cortex was particularly strong for synesthetes who see synesthetic color in the outside world ('projectors') as compared with synesthetes who see the color in their 'mind's eye' only ('associators'). In contrast, greater connectivity (as compared with non-synesthetes) in the superior parietal or frontal cortex did not differentiate between subtypes of synesthesia. In conclusion, we found evidence that increased structural connectivity is associated with the presence of grapheme-color synesthesia, and has a role in the subjective nature of synesthetic color experience.

  1. Department of Psychology, University of Amsterdam, Roetersstraat 15, 1018WB Amsterdam, The Netherlands.

Correspondence to: Romke Rouw1 e-mail:


These links to content published by NPG are automatically generated.


Face to face with cortex

Nature Neuroscience News and Views (01 Aug 2008)