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