Watching the Brain in Action: Functional Neuroimaging

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Watching the Brain in Action Functional
Neuroimaging
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Functional Neuroimaging Activation of Occipital
(Visual) Cortex
Sadato, Pascual-Leone et al., Nature 1996
Brain 1998
Gougoux et al., 2005 PLoS Nature 2004
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Neuroimaging of Occipital Cortex in the Blind
Braille
LATE
EARLY
Burton et al., J. Neurophysiol 2002
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Braille Alexia Following an Occipital Stroke
Case Report
- 63 y.o. right-handed female - blind at birth
(retinopathy of prematurity) - Reported VA
NLP - normal milestones, Braille at 6 y.o. -
proficient reader 120-150 symbols/min
Complaint light-headedness, difficulty
swallowing, motor coordination, LOC - admitted to
Emergency - within 24 hrs alert and
interactive - normal physical and neurological
exam
Hamilton et al., 2000 Neuroreport Merabet et
al., 2004 Neuron
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Transcranial Magnetic Stimulation (TMS)
Generated Magnetic Field
Induced Current
TMS Coil
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Timing of Tactile Performance Early Blind
Effect of Chronometry on Braille Reading
Number of Stimuli
Somatosensory Cortex
10
20
30
40
50
60
70
80
90
100
110
Detected
No TMS
or
Perceived
Occipital Cortex
10
20
30
40
50
60
70
80
90
100
110
No TMS
Delay Interval (msec)
Pascual-Leone et al., 1999 Neuronal Plasticty
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Neuroplasticity of Somatosensory Cortex in the
Blind
After Training
Before Training
Pascual-Leone et al., 1999
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Neuroplasticity of Somatosensory Cortex in the
Blind
Sterr et al., 1998
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Pietrini et al., PNAS 2004
Identifying Objects Through Touch
Tactile Visual Overlap
tactile and visual
tactile
visual
Blind Subjects
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Verbal memory/Verb generation in blind and sighted
Early Blind
Sighted
Error Rate
Stimulation Site
Stimulation Site

• rTMS in the occipital cortex of the blind
  interferes with verb-generation performance
• most common error type was semantic.

Amedi et al. Nat Neurosci 2004
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Absolute pitch in blind musicians
Right Hemisphere
Higher prevalence of absolute pitch in blind
musicians (55) compared to sighted musicians
(20) despite later musical training.
Left Hemisphere
planum temporale
Hamilton et al., 2004