fMRI localizes brain regions
How do synesthetes process graphemes?
ControlsSynesthetesVO2, VO1, V4, Brewer et al. 2005
In a second experiment, we show movies…
• Realistic grapheme presentation• Achromatic children’s television
How are color and grapheme regions related?
Synesthetes cluster grapheme and color regions during SS audio
Audio
AnteriorRight Left
Tomson et al. 2013
Neuroimaging Summary
• Grapheme and color regions are hyper-connected
• Synesthetes cluster visual regions
• Grapheme and color regions are more clustered in synesthetes than controls
• Take-home: There IS more communication between brain regions in synesthesia. The question now is how MUCH more is necessary for the percept?
Genetics of synesthesia
• Synesthesia Battery for remote phenotyping
• Oragene saliva kids
• 6,090 SNP • Ilumina Linkage 12 Chip
Tomson et al. 2011
Family linkage
CS Synesthete
Unaffected
Verify synesthesia
Eagleman et al. 2007
with synesthete.org
Consistency Results
5
Timed Congruency TestConsistency Test
5
Synesthesia genetics
• Family linkage study– 23 MB region chromosome 16– Heterogeneous
• Whole exome sequencing– Non-coding
• Whole genome sequencing
– Copy number variant– Epigenetic
• Twin studies
• Autosomal dominant incomplete penetrance
Synesthesia Summary• Colored sequence synesthesia is linked to
chromosome 16
• Synesthetes connect grapheme and color regions more than controls
• Synesthetes cluster visual regions during audio stimulation
• Take-home: There IS more communication between brain regions in synesthesia. The question now is how MUCH more is necessary for the percept? What is the genetic mechanism?
Why is this important?
• When brain regions fail to communicate, you get disorders such as Alzheimer’s, Balint’s Syndrome, Autism Spectrum Disorder, and many others.
• Understanding these complex disease states starts with understanding the basic science behind global brain communication.
• Synesthesia is one way to answer these questions.
Synesthetic activity bleeds into color areas
The synesthetic brain
• How do synesthetes process graphemes?
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ControlsSynesthetesVO2, VO1, V4, Brewer et al. 2005