Article by Calvo-Merine, Glaser, Grezes, Passingham, Haggard, 2005. Action Observation and Acquired Motor Skills: An fMRI with Expert Dancers Article by Calvo-Merine, Glaser, Grezes, Passingham, Haggard, 2005. Presented by Stephanie Parent

Introduction: key terms Action observation Observing someone performing an action Acquired motor skills Actions that one has learned to do and mastered. The actions are integrated in the individual’s motor repertoire. MIRROR MECHANISM: The network of motor area involved in execution of an action is also activated by observation of action Mirror mechanism During action observation, the brain stimulate making that action by activating certain motor areas necessary to perform that action

Background: Discovery of the mirror mechanism Monkey mirror mechanism (di Pelligrino, Fadiga, Fogassi, Gallese, Rizzolatti 1992) Neurons in the macaque monkey’s premotor and parietal cortices discharge when the monkey performs an action OR When the monkey observe an action. Human mirror mechanism (Decety and Greze, 2001) Premotor cortex, parietal areas and the superior temporal sulcus (STS) neurons are activated during action observation Is the mirror mechanism tuned to the individual motor repertoire?

Action Observation and Acquired skills: an fMRI on expert dancers (Calvino et al., 2005) Hypothesis During action observation, the mirror system activity (pre-motor & parietal cortices and STS) will be stronger in individuals who have learned to perform that action than those who have not. Experimental task 10 professional ballet dancers, 10 Capoeira dancers and 10 non-dancers (control group) watched videos of ballet and capoeira while their brain activity was recorded in an fMRI. The difference in brain activation between expert dancers and non-expert was the point of interest EXPERIMENTAL TASK: Subjects with different motor experiences and repertoire subjected to identical stimuli

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Results Expertise effect In line with hypothesis: When expert dancers watched their own type of dance, stronger activation (BOLD action) was found in the pre-motor cortex, the parietal area and the STS Expertise effect STRONGER ACTIVATON: The “mirror system” of non-expert was also activated but to a lesser degree Ventral pre-motor 2.dorsal premotor 3. Iinferior Parietal sulcus 4.superior temporal sulcus Note that the same voxels in non-expert control subjects and expert dancers watching another type of dance weren’t as strongly activated. The expertise effect hence depends on the acquired motor skills, not the visual properties. While they all SAW the same stimuli, their brain reacted differently. IN LINE WITH HYPOTHESIS: the brain’s response to seeing an action is influenced by the acquired motor skills of the observer EXPERTISE EFFECT:

Discussion Implications Mirror system codes complete action patterns, not just individual movement Mirror system is sensitive to much more abstract levels of action organisation Skilled movements, meaningful movements 1ST POINT: Ballet and Capoeira have similar components at the muscle level (ex, both involve jumping). Both groups of dancers can perform similar movement, yet their mirror system reacted differently. 2ND POINT:ABSTRACT LEVEL OF ACTION ORGANISATION, such as those that differentiate dance style SKILLED, MEANINGFUL MOV: mirror system is not concerned with muscles but with a higher level of organisation

Strengths of the article Experimental design eliminates counfounds Ballet and capoeira movements are kinetically comparable Brain activation differences are not due to differences in kinetic Dancers on video were matched in body shape and clothing and their faces were blurred Subject can’t process facial/emotional features All subjects were right-handed males aged 18-28 with normal vision and no mental illness history Diminishes individual differences Kinetically comparable: The movements were matched by a professional choregrapher according to speed, part of the body employed, body location in space, direction of the body movement. List of counfounds eliminated is NOT EXHAUSTIVE

Stimuli: Colour videos of standard classical ballet and capoeira movements were performed by professional dancers Calvo-Merino, B. et al. Cereb. Cortex 2005 15:1243-1249; doi:10.1093/cercor/bhi007 Copyright restrictions may apply.

Limitations Article focused on predicted area (motor), but the expertise effect activated other areas, some related to emotional experience Ventromedial frontal lobe Responds to pleasurable/rewarding stimuli & social judgement Parahippocampal gyrus Responds to meaningful rather than meaningless actions Next Step: Analyzing how the expertise effect is associated with emotional experience. VENTROMEDIALFRONTAL LOBE: Experts may show this activation because it is especially rewarding for them or because they have greater social engagement with the person they observe. PARAHIPPOCAMPAL GYRUS: Acton that appear meaningless to inexperts subjects appear more meaningful to experts Degree of engagement between the viewer and the stimuli during action observation