title: [Synesthesia as a neuronal palimpsest].
abstract: Synesthetes, a small fraction of the population, experience systematic, additional associations. For example, they may arbitrarily associate a specific color to each letter or number. Synesthesia has offered for the last ten years to cognitive science a unique opportunity to study the neural bases of subjective experience, drawing on individual differences just like in neuropsychology, but with healthy people. Here we review the current knowledge and propose a new theory, the "palimpsest hypothesis", a variant of the recycling hypothesis for reading. The neural development of written language expertise (a recent cultural invention acquired without any genetic modification) requires indeed the recycling of brain regions predisposed to expertise acquisition into reading regions. The palimpsest hypothesis supposes that for synesthetes recycling involves neuronal networks that were already specialized for color perception. Synesthetic colors would be the remains of this former expertise.
authors.affiliation: Centre de recherche cerveau et cognition (CERCO), université de Toulouse et CNRS UMR 5549, pavillon Baudot, centre hospitalier-universitaire (CHU) Purpan, BP 25202, 31052 Toulouse Cedex 3, France. jean-michael.hupe@cerco.ups-tlse.fr
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Hupé
mesh_terms: D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D003118:Color Perception / Q000502:physiology; D025461:Feedback, Physiological; D006801:Humans; D007206:Individuality; D008959:Models, Neurological; D008960:Models, Psychological; D009415:Nerve Net / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D010465:Perception / Q000502:physiology*; D010468:Perceptual Disorders / Q000503:physiopathology* / Q000523:psychology; D011581:Psychological Tests; D011932:Reading; D009435:Synaptic Transmission