Technical report: Event-related fMRI adaptation paradigm on real and synesthetic colors
Jean-Michel Hupé (1)*, Cécile Bordier (2), Michel Dojat (2)

Publication date on the CerCo website: September 12th, 2011

(1) CerCo, Université de Toulouse & CNRS, 31300 Toulouse, France
(2) Grenoble Institut des Neurosciences (GIN) - INSERM U836 & Université Joseph Fourier, 38700 La Tronche, France

*corresponding author
CNRS CerCo UMR 5549, Pavillon Baudot CHU Purpan, BP 25202, 31052 Toulouse Cedex
email :      tel: 33 (0)5 81 18 49 43

The subjective experience of color by synesthetes when viewing achromatic letters and numbers supposedly relates somehow to real color experience. Using fMRI, we tried to specify the degree of coactivation by real and synesthetic colors, by evaluating each color center individually and applying adaptation protocols across real and synesthetic colors. Indeed, fMRI activation of the same voxels by real and synesthetic colors would not be enough to prove that the same neurons are involved, given the relatively weak anatomical resolution of the BOLD signal (≈ 3mm). We therefore performed fMRI event-related adaptation protocols on 10 synesthetes in order to measure possible cross-adaptation effects when mixing real and synesthetic colors. However, to start with, we did not find any region that was activated both by real and synesthetic colors. We did not observe any clear adaptation for synesthetic colors in color ROIs, but we also did not observe any systematic color adaptation in retinotopic V4 or in color ROIs, so we could not test rigorously our hypothesis of adaptation across real and synesthetic colors.

You may download the pdf file here.

This technical report should be read in complement to:

The neural bases of grapheme-color synesthesia are not localized in real color-sensitive areas
Jean-Michel Hupé, Cécile Bordier, Michel Dojat

Cerebral Cortex 2011; doi:10.1093/cercor/bhr236
first published online
September 12, 2011

links AbstractFull TextPDF

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