1. NeuroImage 50 (2010) 1148–1167 ALE meta-analysis of action observation and imitation in the human brain Svenja Caspers,Karl Zillesa, Angela R.Laird, SimonB.Eickhoff

2. Background Mirror neuron system in the macaque brain (Gallese et al., 1996) Evidence for possible “mirror areas” in humans based on functional neuroimaging experiments Observation and imitation are closely related Are observation and imitation sustained by the same neuronal networks?

3. AIM Identification of cortical areas consistently involved in action observation and imitation… … by a quantitive (coordinate based) meta-analysis of the current neuroimaging literature

4. Materials & Methods 139 experiments (fMRI and PET),1289 subjects, 1932 activation foci ( Talairach, MNI coordinates) Tasks, effectors and instructions

5. Material & Methods Activation likelihood estimation (ALE) algorithm 1 study 1 Map Foci from all studies Many foci Each foci = centre of a 3D Gaussian probability distribution InputOutput Union activation modelled map (MA) Voxel-wise ALE scores True convergence? Comparison of “true” scores with scores in null distribution (baseline activation)

6. Symmetrical activation across both hemispheres Action Observation Network

8. Action Observation Network… …subanalysis for effectors

9. No FFA/FBA activation BA45 only in right hemisphere As hand observation but with lower statistical power FFA/FBA only in right hemisphere hIP3 only in left hemisphere (the only consistent parietal activation) As nonHand observation No consistent SMA activation

10. Contrast analysis between hand action observation and observation of non-hand actions A: hand observation C : non-hand observation

11. Action Observation Network… …subanalysis for instructions Comparable network to main analysis No parietal activation Consistent activation of dPMC-BA6, pMTG and extrastriate areas

12. Contrast analysis between the two instructions No stronger activation for the instruction “observe to imitate” in any region BUT only 8 experiments were used A: passively observe B : observe to imitate

13. Action Observation Network… …subanalysis for object- related hand actions Bilaterally: BA 44, BA6, IPL- PFt, SPL (7a), pMTG,V5 Right hemisphere: S1, IPS- hIP3 Activation of temporo- occipital areas

14. Contrast analysis between object-related hand actions and non-object-related hand action A: object-related hand action B : non-object-related hand action

15. Action Imitation Network Bilaterally: BA 44, BA 6, SMA, SFG, S1 (area 2), IPL-PFt, V5 Left hemisphere: pMTG Right hemisphere: IPL-PFcm, FFA/FBA, frontal aspect of insular cortex

16. Action Imitation Network… …subanalysis for effectors Comparable to the main analysis pMTG bilaterally activated Activation of BA 4, BA 6, BA 44 SFG No temporo-occipital activation

17. Conjunction analyses Bilaterally: BA 44, BA 6, SMA, PFt, PFop, S1 (area 2), V5 Left hemisphere: pMTG Right hemisphere: FFA/FBA

18. Contrast analyses ObservationImitation Rostro-dorsal part of BA 44 (area BA45- bilaterally) Caudo-ventral part of BA 44 (bilaterally) BA 6, pMTG, V5 (bilaterally) IPL-PFt/Pfop (left hemisphere) SPL (right hemisphere)S1 (area 2),IPL-PFt, FFA/FBA (right hemisphere)

19. Discussion Methodological considerations Coordinate based meta-analysis vs. image based meta-analysis Potential presence of confounding factors No information for the strength of resulting activation Account for sample size

20. Discussion Areas involved in each network Expanded Mirror Neuron System In humans, observation and imitation networks are similar, if not the same (differences in macaque brain) BA 44 and PFt/hIP3 homolog to F5 and PFG/PF of macaque respectively BA 44 => initiation and termination of simple actions (imitation) BA 45 =>supraordinate aspect of action SMA mainly activated in non-hand tasks pMTG involved in the processing of biological motion V5 involved in motion perception FFA/FBA serves as an encoder of facial and body stimuli S1-top down modulation from associative areas

21. Discussion Neural correlates of action observation Transient inactivation of observation network- related areas result in impairment of action observation ability Somatotopy of the involved parts of observation network? Activation’s independency from the effectors Possible functions of the network: - Feedback control of an action (SPL, IPS, BA 6)-optic ataxia - Implicit processing of object features and their integration within the observed motor act (fronto-parietal areas) - Composition of the appropriate motor program (dPMC) Neural correlates of action imitation Bilateral pattern of activation

22. Thank you!