Individual Differences among Grapheme-Color Synesthetes: Brain-Behavior Correlations

Grapheme-color synesthetes experience specific colors associated with specific number or letter characters. To determine the neural locus of this condition, we compared behavioral and fMRI responses in six grapheme-color synesthetes to control subjects. In our behavioral experiments, we found that a...

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Bibliographic Details
Published inNeuron (Cambridge, Mass.) Vol. 45; no. 6; pp. 975 - 985
Main Authors Hubbard, Edward M., Arman, A. Cyrus, Ramachandran, Vilayanur S., Boynton, Geoffrey M.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 24.03.2005
Elsevier Limited
Subjects
Brain
Brain Mapping
Cerebrovascular Circulation - physiology
Color Perception - physiology
Color Vision Defects - physiopathology
Feedback
Functional Laterality - physiology
Humans
Illusions - physiology
Magnetic Resonance Imaging
Medical imaging
Neuropsychological Tests
Observer Variation
Pattern Recognition, Visual - physiology
Photic Stimulation
Time series
Visual Cortex - anatomy & histology
Visual Cortex - physiology
Visual Pathways - anatomy & histology
Visual Pathways - physiology
Visual task performance
Online AccessGet full text
ISSN0896-6273
1097-4199
DOI10.1016/j.neuron.2005.02.008

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Summary:Grapheme-color synesthetes experience specific colors associated with specific number or letter characters. To determine the neural locus of this condition, we compared behavioral and fMRI responses in six grapheme-color synesthetes to control subjects. In our behavioral experiments, we found that a subject’s synesthetic experience can aid in texture segregation (experiment 1) and reduce the effects of crowding (experiment 2). For synesthetes, graphemes produced larger fMRI responses in color-selective area human V4 than for control subjects (experiment 3). Importantly, we found a correlation within subjects between the behavioral and fMRI results; subjects with better performance on the behavioral experiments showed larger fMRI responses in early retinotopic visual areas (V1, V2, V3, and hV4). These results suggest that grapheme-color synesthesia is the result of cross-activation between grapheme-selective and color-selective brain areas. The correlation between the behavioral and fMRI results suggests that grapheme-color synesthetes may constitute a heterogeneous group.
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ISSN:0896-6273
1097-4199
DOI:10.1016/j.neuron.2005.02.008