title: A critical review of the neuroimaging literature on synesthesia.
abstract: Synesthesia refers to additional sensations experienced by some people for specific stimulations, such as the systematic arbitrary association of colors to letters for the most studied type. Here, we review all the studies (based mostly on functional and structural magnetic resonance imaging) that have searched for the neural correlates of this subjective experience, as well as structural differences related to synesthesia. Most differences claimed for synesthetes are unsupported, due mainly to low statistical power, statistical errors, and methodological limitations. Our critical review therefore casts some doubts on whether any neural correlate of the synesthetic experience has been established yet. Rather than being a neurological condition (i.e., a structural or functional brain anomaly), synesthesia could be reconsidered as a special kind of childhood memory, whose signature in the brain may be out of reach with present brain imaging techniques.
authors: Centre de Recherche Cerveau et Cognition, Université de Toulouse and Centre National de la Recherche Scientifique, Toulouse France.
authors: Jean-Michel
authors: JM
authors: Hupé
authors: Grenoble Institut des Neurosciences, Institut National de la Santé et de la Recherche Médicale U836 and Université Grenoble Alpes, Grenoble France.
authors: Michel
authors: M
authors: Dojat
keywords: DTI; VBM; connectivity; fMRI; synesthesia