SynesthesiaSynesthesia Your brain and Steffie Tomson, Ph.D. UCLA Geffen School of Medicine [email protected].

Synesthesia

Your brain and

Steffie Tomson, Ph.D.UCLA Geffen School of Medicine

[email protected]

The Brain

Brains have many distinct regions & functions

Neurons communicate via synapse

How do brain regions communicate?

Balint’s Syndrome

LINELINE

synesthesia

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be

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tsu

fa

c

m

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713…

How do we study synesthesia?

C

Primate?

No way to verify synMouse?

No color vision

Humans: functional MRI(fMRI)

fMRI signal

Source: Arthurs & Boniface, 2002, Trends in Neurosciences

“713”

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?

713…

Humans: functional MRI (fMRI)

Synesthetes cluster visual regions during SS audio

Tomson et al. 2013

Audio

AnteriorRight Left

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.

[email protected]

Function

When Things Go Wrong

Genetics of synesthesiaWhole exome sequencing

Brain Cells

Purkinje Cell Mossy Fibers

Hotspot on chromosome 16between 52 – 76 MBP

Family linkage analysis

Tomson et al. 2011

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

Functional Connectivity

R=.88

R=.23

Brain region 1Brain region 2

Brain region 3Brain region 4

Time

Act

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