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Motor cortical areas: the homunculusThe motor system
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Major Cortical areas involved in planning and execution of “purposeful” movements
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Directional Tuning of MI Cells
Movement onset
(Georgopoulos et al 1982)
P.D.
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Set related responses in Pre-motor Cortex
Prepare LEFT movement Prepare RIGHT movement
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Mirror neurons
Rizzolatti et al., 1996
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Basic properties of the Mirror Neurons
Rizzolatti et al. 1996
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A multimodal representation of action
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Mirror neurons in the Parietal cortex: Intention understanding?
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Mirror neurons show the same specificity when actions are
preformed by the experimenter
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What is represented by the MN?Actions or goals?
Hand
unit210 unit199
Umlita et al., 2008closure
opening
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The mirror system – abstract representation of movement goals?
• Recordings from 37 mirror neurons in F5 in a “hidden action” paradigm
• 19/37 mirror neurons responded significantly in the hidden condition.
• 7/19 – strong responses (hidden=visual)
(Umilta et al., 2001).
Full vision
Hidden vision
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The mirror system in humans
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Cortical activation during observation of mouth hand
and foot action
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Shmuelof & Zohary 2006
Viewed-Hand identity effects in parietal cortex
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Visual and motor hand areas in the human parietal cortex
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Specificity of visually defined “hand areas” to motor actions
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Human mirror system
Dinstein, J. Neuroscience (2008)
Executed
Observed
fMR
I re
spon
se
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Selectivity
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FistHang loose
Thumbsup
The finger
Hang loosemirror neuron
The fingermirror neuron
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Monkey mirror neurons
Gallese, Brain (1996)
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A deeper understanding of “mirror like voxels”
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Mirror neurons should show cross-modal adaptation
Mirror regions should be active both during viewing action and motor action
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Adaptation
First presentation
Repeated presentation
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Movement selective adaptation
Repeats Non-repeats
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Visual adaptation
Observe Observe Observe Observe
Repeats Non-repeats
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Motor adaptation
Execute Execute Execute Execute
Repeats Non-repeats
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Cross-modal adaptation
Execute Observe Execute Observe
Repeats Non-repeats
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Cross-modal adaptation
Observe Execute Observe Execute
Repeats Non-repeats
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Rock paper scissorsDinstein 2008
Get extra $10 if you win more than you lose!
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Game Timeline
Observe
Time
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Execute
Time
Game Timeline
Observe
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Repeat Non-repeat
Execute
Time
Game Timeline
Observe
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Repeat Non-repeat
Execute
Time
Game Timeline
Observe
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Repeat Non-repeat
Execute
Time
Game Timeline
Observe
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Repeat Non-repeat
Execute
Time
Game Timeline
Observe
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Repeat Non-repeat
Execute
Time
Game Timeline
Observe
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Observe
Repeat Non-repeat
Execute
Time
Game Timeline
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Visual adaptation
Green: observed non-repeat > repeat
Mirror system areas
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Motor adaptation
Purple: executed non-repeat > repeat
Mirror system areas
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Motor & visual adaptation
Yellow: overlap of motor and visual adaptation
Mirror system areas
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Motor & visual adaptation
Yellow: overlap of motor and visual adaptation
No cross modal adaptation
Mirror system areas
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ROI Analysis
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Adaptation summary
1. Selectivity for movements in “Mirror system” areas.
2. Adaptation may be taking place in a single population of mirror neurons and/or in two separate populations of visual and motor neurons adapting independently.
3. We now have a way of studying movement selective responses; the critical feature of neural populations involved in movement perception.
Dinstein J. Neurophysiology 2007
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ClassificationTypical mirror region
= ~ 300 voxels
Executed Observed
fMR
I re
spon
se
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Classification
Executed
fMR
I re
spon
se
No specificity in the overall fMRI signal (across voxels)
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Classification
Specificity in the fMRI signal (within voxels)
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Movement selective patterns
Strong Weak
Activation level
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Are patterns distinct & reproducible?
Trial #1
.… .… .…
Execute Execute Execute
Trial #2
Trial #3
Trial #4
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Are patterns distinct & reproducible?
Trial #1
.… .… .…
Observe Observe Observe
Trial #2
Trial #3
Trial #4
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Classify movement patternsD
ecod
ing
accu
racy
R P SExecute
dObserved
R P S
Primary motor & somatosensory
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Classify movement patternsD
ecod
ing
accu
racy
R P SExecute
dObserved
R P S
Early visual areas
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Classify movement patternsD
ecod
ing
accu
racy
R P SExecute
dObserved
R P S
Ventral premotor
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Classify movement patternsD
ecod
ing
accu
racy Left Right
R P S
R P S
R P S
R P SExecute
dObserved
Executed
Observed
Anterior intraparietal sulcus
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Different patterns across modalities
Executed to observed
Observed to executed
R P S
R P S
R P S
R P S
Left aIPS Right aIPS
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Execute
Different patterns across modalities
Observe