SynesthesiaSynesthesia Your brain and Steffie Tomson, Ph.D. UCLA Geffen School of Medicine...
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Transcript of SynesthesiaSynesthesia Your brain and Steffie Tomson, Ph.D. UCLA Geffen School of Medicine...
The Brain
Brains have many distinct regions & functions
Neurons communicate via synapse
How do brain regions communicate?
Balint’s Syndrome
LINELINE
synesthesia
jv
be
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tsu
fa
c
m
73
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.
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?
>
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
ivit
y
