An fMRI Study of Sound-Color Synesthesia
Abstract
This study examines three subjects with different types of synesthesia: Grapheme-color, Sound-color, & Color-gustatory synesthesia. Functional MRI (fMRI) will be used to monitor brain activation in subjects and age-matched controls.
The study goals are to determine if activation of brain regions will vary dependent upon the synesthesia type and to ascertain if similar activation patterns will emerge when learned tasks are associated with previously known stimuli. Two studies will be conducted coupled with fMRI analyses.
(1) Baseline analysis and cross-comparison of the three synesthetes. Subjects will be exposed to stimuli that trigger synesthetic experiences followed by conditions that do not elicit synesthesia.
(2) Learning study with the color-grapheme synesthete. The subject will be presented with unknown symbols that do not trigger a synesthetic experience. After the subject learns to associate meaning with these symbols, these symbols should produce a synesthetic experience. 
What is synesthesia?
Synesthesia is characterized by excitation of a sensory pathway followed by involuntary activation of additional sensory pathways. Synesthetes may hear sounds in response to smell, see colors when they hear words, or taste shapes; synesthesia can involve any of the senses.
Sound-Color - Vividly colored shapes (photisms) are seen during auditory input. For example, when describing a woman’s voice TH reports that the photism it elicits is, “Yellow with silver on the edges, and its shape quivers like an accordion.”
Grapheme-Color - Automatic involuntary experience of seeing colors when viewing numbers, letters, or words. DR, when viewing the letter “B” sees “Flickering orange and blue over the letter.”
Color-Gustatory - Certain color patterns evoke sensations of taste. EC reports that yellow, “Tastes like the icing on a cake, but sweeter.”
Click here to view the poster that was presented [ppt]
