distinguishing between self and other: how shared are shared representations? marcel brass

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


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)


The direct matching hypothesis

Action observation leads to an activation of an internal motor representation.


Open questions

• Why don‘t we imitate all the time?

• Why don‘t we confuse internally generated and externally triggered motor representations?


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


The imitation-inhibition task

congruent incongruentbaseline

Brass et al. (2000)


Brass et al. (2000)

++

Lift the index finger when a `1` appearsand the middle finger when a `2` appears.

The imitation-inhibition task


Results

Brass et al. (2000)

inconbasecon


Patients

• 16 patients with frontal lesions of different etiology and lesion site

• 14 patients with posterior lesions (temporal, parietal)

• 16 age-matched controls


Results

Brass et al. (2003)

0

2

4

6

8

10

Interferenz(%)

Imitation-inhibition task

frontal posterior control

* *

interference score: incongruent errors (%) – congruent errors (%)


Conclusions

• Patients with frontal lesions have problems to inhibit imitative response tendencies.


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.


Experimental design

• ten healthy right handed participants• the imitation-inhibition task

• functional Magnetic Resonance Imaging (fMRI)


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)


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)


Conclusions

The inhibition of imitative behaviour seems to involve mechanisms related to self-other distinction.


The mirroring of contextual information

• Are environmental constraints mapped onto the observer’s motor representation?


Prediction

Observing a physical restraint in another person should restrain the observer.


Paradigm

no restraint corresponding restraint non-corresponding restraint


Demonstration


Results


Alternative hypothesis

The slowing effect is due to higher perceptual difficulty in the corresponding restraint condition.


Test

no restraint corresponding restraint

if a ‘1‘ appears if a ‘2‘ appears

Stimuli

Responses


Results


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.


Roman LiepeltStephanie SpenglerMichael SteinbornHarold Bekkering

Jan DerrfussWolfgang Prinz

D. Yves von Cramon

distinguishing between self and other: how shared are shared representations? marcel brass

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