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Motor cortical
areas: the
homunculus
The motor
system
Major Cortical areas involved in planning and
execution of “purposeful” movements
Directional Tuning of
MI Cells
Movement onset
(Georgopoulos et al 1982)
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?
unit210
opening
Hand
Umlita et al., 2008
closure
unit199
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)
Full
vision
Hidden
vision
(Umilta et al., 2001).
The mirror system in humans
Cortical activation during
observation of mouth hand
and foot action
Viewed-Hand identity effects in parietal cortex
Shmuelof & Zohary 2006
Visual and motor hand areas in the
human parietal cortex
Specificity of visually defined “hand
areas” to motor actions
fMRI response
Human mirror system
Execute
Observe
Dinstein, J. Neuroscience
(2008)
Selectivity
Hang loose
mirror
neuron
Hang
loose
Fist
The finger
mirror
neuron
The
finger
Thumbs
up
Monkey mirror neurons
Gallese, Brain (1996)
A deeper understanding of
“mirror like voxels”
Mirror regions should be active both
during viewing action and motor action
Mirror neurons should show
cross-modal adaptation
Adaptation
First
presentation
Repeated
presentation
Movement selective
adaptation
Repeats
Non-repeats
Visual adaptation
Repeats
Observe
Observe
Non-repeats
Observe
Observe
Motor adaptation
Repeats
Execute
Execute
Non-repeats
Execute
Execute
Cross-modal adaptation
Repeats
Execute
Observe
Non-repeats
Execute
Observe
Cross-modal adaptation
Repeats
Observe
Execute
Non-repeats
Observe
Execute
Rock paper scissors
Dinstein 2008
Get extra $10 if you win more than you lose!
Game Timeline
Observe
Time
Game Timeline
Observe
Execute
Time
Game Timeline
Observe
Execute
Time
Repeat
Non-repeat
Game Timeline
Observe
Execute
Time
Repeat
Non-repeat
Game Timeline
Observe
Execute
Time
Repeat
Non-repeat
Game Timeline
Observe
Execute
Time
Repeat
Non-repeat
Game Timeline
Observe
Execute
Time
Repeat
Non-repeat
Game Timeline
Observe
Execute
Time
Repeat
Non-repeat
Visual adaptation
Mirror system areas
Green: observed non-repeat > repeat
Motor adaptation
Mirror system areas
Purple: executed non-repeat > repeat
Motor & visual adaptation
Mirror system areas
Yellow: overlap of motor and visual adaptation
Motor & visual adaptation
Mirror system areas
Yellow: overlap of motor and visual adaptation
No cross modal adaptation
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
Classification
fMRI response
Typical mirror region
= ~ 300 voxels
Executed
Observed
Classification
fMRI response
No specificity in the overall
fMRI signal (across voxels)
Executed
Classification
Specificity in the fMRI signal (within voxels)
Movement selective patterns
Activation level
Strong
Weak
Execute
Execute
Execute
….
….
….
Are patterns distinct &
reproducible?
Trial #1
Trial #2
Trial #3
Trial #4
Are patterns distinct &
reproducible?
Observe
Observe
Observe
Trial #1
Trial #2
Trial #3
….
….
….
Trial #4
Classify movement patterns
Decoding accuracy
Primary motor & somatosensory
R
P
S Execute
d
R
P
SObserve
d
Classify movement patterns
Decoding accuracy
Early visual areas
R
P
S Execute
d
R
P
SObserve
d
Classify movement patterns
Decoding accuracy
Ventral premotor
R
P
S Execute
d
R
P
SObserve
d
Classify movement patterns
Anterior intraparietal sulcus
Decoding accuracy
Left
R
P
SExecute
d
R
P
S
Observe
d
Right
R
P
S
Execute
R
P
S
Observe
Different patterns across
modalities
Left aIPS
R
S
P
R
S
Right aIPS
P
Executed to
observed
Observed to
executed
R
S
P
R
S
P
Different patterns across
modalities
Observe
Execute