Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Distinguishing between self and other: How shared are shared representations?
Marcel Brass
MAXPLANCK
INSTITUTE
FOR
HUMANCOGNITIVE AND BRAIN SCIENCESDEPARTMENT OF COGNITIVE NEUROLOGYLEIPZIG
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Observation and execution of action are closely linked
• Cognitive psychology
– movement observation has a strong influence on movement execution (Brass et al., 2000, 2001, Stuermer et al., 2000)
• Social psychology
– chameleon effect (Chartrand & Bargh, 1999)
• Brain imaging
– activation of motor related areas by action observation (e.g. Grezes & Decety, 1999)
• Neurophysiology
– mirror neurons (e.g. Rizzolatti & Craighero, 2004)
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
The direct matching hypothesis
Action observation leads to an activation of an internal motor representation.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Open questions
• Why don‘t we imitate all the time?
• Why don‘t we confuse internally generated and externally triggered motor representations?
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Neuropsychological findings
• Luria (1966)
– prefrontal patients show echopractic response tendencies
• Lhermitte et al. (1986), DeRenzi et al. (1996)
– patients with prefrontal lesions show overt imitative behavior
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
The imitation-inhibition task
congruent incongruentbaseline
Brass et al. (2000)
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Brass et al. (2000)
++
Lift the index finger when a `1` appearsand the middle finger when a `2` appears.
The imitation-inhibition task
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Results
Brass et al. (2000)
inconbasecon
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Patients
• 16 patients with frontal lesions of different etiology and lesion site
• 14 patients with posterior lesions (temporal, parietal)
• 16 age-matched controls
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Results
Brass et al. (2003)
0
2
4
6
8
10
Interferenz(%)
Imitation-inhibition task
frontal posterior control
* *
interference score: incongruent errors (%) – congruent errors (%)
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Conclusions
• Patients with frontal lesions have problems to inhibit imitative response tendencies.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Functional mechanisms involved in the inhibition of imitative behavior
• Hypothesis
1. The inhibition of imitative behavior involves general inhibitory mechanisms.
2. The inhibition of imitative behavior involves specific mechanisms related to the distinction of self-generated and externally triggered motor representations.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Experimental design
• ten healthy right handed participants• the imitation-inhibition task
• functional Magnetic Resonance Imaging (fMRI)
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Imitation-inhibition task
Incongruent vs. congruent
Brass, Derrfuss & von Cramon (2005)
1
2
1
2
anterior fronto-median cortex (aFMC)
temporo-parietal junction area (TPJ)
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
The functional role of the anterior fronto-median cortex and the TPJ
– sense of agency (e.g. Farrer et al., 2003)
– perspective taking (Ruby & Decety, 2001, 2003)
– out of body experience (Blanke et al., 2002)
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Conclusions
The inhibition of imitative behaviour seems to involve mechanisms related to self-other distinction.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
The mirroring of contextual information
• Are environmental constraints mapped onto the observer’s motor representation?
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Prediction
Observing a physical restraint in another person should restrain the observer.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Paradigm
no restraint corresponding restraint non-corresponding restraint
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Demonstration
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Results
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Alternative hypothesis
The slowing effect is due to higher perceptual difficulty in the corresponding restraint condition.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Test
no restraint corresponding restraint
if a ‘1‘ appears if a ‘2‘ appears
Stimuli
Responses
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Results
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Summary
• There is an automatic tendency to imitate observed behaviour.
• Prefrontal patients have problems to inhibit imitative response tendencies.
• The inhibition of imitative behaviour involves functional mechanisms related to self-other distinction.
• Not only the action itself is mapped onto the observer’s motor representation but also environmental constraints.
Max Planck Institute for Human Cognitive and Brain Sciences04.2006
Roman LiepeltStephanie SpenglerMichael SteinbornHarold Bekkering
Jan DerrfussWolfgang Prinz
D. Yves von Cramon
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