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Updated: May 8, 2026
10:27
Training Synesthetic Letter-color Associations by Reading in Color
Published on: February 20, 2014
Neural networks of colored sequence synesthesia.
Steffie N Tomson1, Manjari Narayan, Genevera I Allen
1Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA. steffietomson@gmail.com
Summary
Synesthesia involves unusual sensory associations. This study found synesthetes exhibit increased brain connectivity, particularly in visual regions, during grapheme-related tasks, suggesting network dynamics explain their experience.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychology
Background:
- Synesthesia links stimuli to anomalous associations, like colors with letters (grapheme-color synesthesia).
- Previous research explored synesthesia via resting-state or stimulus-driven connectivity, but network dynamics across conditions remain unclear.
Purpose of the Study:
- To investigate how subtle changes in brain network properties explain synesthetic experiences.
- To construct a functional network of synesthesia using functional MRI (fMRI).
- To explore functional connectivity differences between synesthetes and controls during various grapheme stimulation conditions.
Main Methods:
- Functional MRI (fMRI) was used to identify grapheme-specific brain regions in humans.
- A functional 'synesthetic' network was constructed.
- Functional connectivity was analyzed using Markov networks during rest, auditory grapheme stimulation, and audiovisual grapheme stimulation.
Main Results:
- Synesthetes showed increased network connections during rest and auditory grapheme stimulation compared to controls.
- Synesthetes' brain activity clustered in visual regions, while controls' clustered in parietal and frontal regions.
- Synesthetes demonstrated heightened connectivity between grapheme and color regions and greater use of visual areas during dynamic grapheme stimulation.
Conclusions:
- Synesthesia is characterized by increased connectivity between grapheme and color processing regions.
- Synesthetes utilize visual brain regions more extensively than controls when processing graphemes.
- Global network dynamics, rather than individual region properties, better characterize synesthesia.
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