Motor cortical areas the homunculus The motor system

Motor cortical areas: the homunculus The motor system

Major Cortical areas involved in planning and execution of “purposeful” movements

Directional Tuning of MI Cells P. D . 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? unit 210 opening Hand Umlita et al. , 2008 closure unit 199

The mirror system – abstract representation of movement goals? • Recordings from 37 mirror neurons in F 5 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 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

f. MRI response Human mirror system Executed 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 Non-repeats Observe

Motor adaptation Repeats Execute Non-repeats 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 f. MRI response Typical mirror region = ~ 300 voxels Executed Observed

Classification f. MRI response No specificity in the overall f. MRI signal (across voxels) Executed

Classification Specificity in the f. MRI signal (within voxels)

Movement selective patterns Activation level Strong Weak

Execute …. …. Are patterns distinct & reproducible? Trial #1 Trial #2 Trial #3 Trial #4

Are patterns distinct & reproducible? Observe Trial #1 Trial #2 Trial #3 …. …. Trial #4

Classify movement patterns Decoding accuracy Primary motor & somatosensory R P SExecuted R P SObserve d

Classify movement patterns Decoding accuracy Early visual areas R P SExecuted R P SObserve d

Classify movement patterns Decoding accuracy Ventral premotor R P SExecuted R P SObserve d

Classify movement patterns Anterior intraparietal sulcus Decoding accuracy Left R P S S Observe Executed d Right R P S S Executed Observe

Different patterns across modalities Left a. IPS R P S Right a. IPS R Executed to observed Observed to executed P S R P S

Different patterns across modalities Observe Execute