W Max Planck Institute for Human Cognitive and Brain Sciences The role of the posterior prefrontal...

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Max Planck Institute for Human Cognitive and Brain Sciences

The role of the posterior prefrontal cortex in task

preparation

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Jan Derrfuss

Birte Forstmann

Hannes Ruge

Iring Koch

Nachshon Meiran

Orit Rubin

Markus Ullsperger

Thomas Knösche

D.Yves von Cramon

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The fronto-lateral cortex

dorsolateral

ventrolateral

inferior-frontal junction (IFJ)

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Neuronal correlates of task-switching

Dove et al. (2000)

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Cognitive processes involved in task-switching

a) preparation related control processes

• task preparation reduces switch-costs

b) execution related control processes

• even with optimal preparation there are residual costs

Processes involved in task-switching

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The task-cueing paradigm

cue taskpreparation

Cue-target interval (CTI)

By presenting a cue in advance to the task one can

separate cue-related and target related processes.

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Separating task preparationfrom execution-related control

• A number between 20 and 40 (not 30) was displayed.

• Magnitude task: Is the number greater or smaller 30?

• Parity task: Is the number odd or even?

• A cue indicated which task to execute.

magnitude task parity task

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Experimental paradigm

33 33

Fixation0-200 ms

Cue400-1600 ms

Target1600-2400 ms

Response

withpreparation

withoutpreparation

onlypreparation null

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Demonstration of a trial

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Behavioral resultsR

ea

cti

on

tim

e

(ms

)

750

800

850

900

950

1000

1050withoutpreparation

withpreparation

repeat switch

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Cue-related activation

Brass & von Cramon (2002)

cueing effect (ms)

100 150 200 250 300 350 400

signal change (%)0,0

0,2

0,4

0,6

0,8

preSMAr=.57

r=.63IFJ

cueing effect (ms)

100 150 200 250 300 350 400

signal change (%)

-0,1

0,0

0,1

0,2

0,3

0,4

0,5

IFj r=.63

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Conclusion

• The IFJ and the preSMA are involved in task preparation.

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Open question

• Are these areas involved in the encoding of the cue or the

updating of the task representation?

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Decomposing components of task preparation

• By assigning two cues to each task one can dissociate cue

encoding from task-set updating

= parity judgment= magnitude judgment

cue repetition

cue switch

meaning switch

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Decomposing components of task preparation

• within-trial manipulation of cue-related processing

task

Processing related tocue 1

cue 1 cue 2

Processing related tocue 2

taskcue 1 cue 2

long CTI

short CTI

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Experimental paradigm

33 33

Fixation0-200 ms

Cue 2 (100 ms)

Response

CCI=700

33

333333

Cue 1 (100 ms)

Cue 1 (100 ms)

Target

Target

CTI=60/700

CTI=60/700

Response

cuerepetion

cueswitch

meaningswitch

singlecue

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33


32

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Behavioral results

long CTIshort CTI

repe

titio

n

Cue-s

witc

h

Mea

ning

-

switc

h

repe

titio

n

Cue-s

witc

h

Mea

ning

-

switc

h

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Meaning-switch versus cue-switch

z > 3.1


IFJ

Intra-parietal sulcus

Inferior frontal gyrus

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Signal change analysis

cue-repetiton

cue-switch

meaning-switch

left IFJ

cue-repetiton

cue-switch

meaning-switch

IPS

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0 1 2 3 4

signal change (%)

0,42

0,44

0,46

0,48

0,50

0,52

preSMA

cue-repetiton

cue-switch

meaning-switch

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Who comes first?

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5

FCzcue switch, meaning repeat

cue switch, meaning switch

meaning switch - meaning repeat

difference waveERPA B

C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

abstract task representation concrete task representation

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Who comes first?

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

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Who comes first?

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

Brass, Ullsperger, Knösche & Phillips (in preparation)

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Conclusions

• The IFJ and the IPS are related to the activation of task

representations.

• There is a hierachical order of prefrontal and parietal cortex

in task preparation.

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Manipulating the association of cue and task

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

• integrating information over time

• distinguishing relevant from irrelevant information

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Manipulating the association of cue and task

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

magnitude

parity

Task cues

switch

repeat

Transition cues

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The paradigm

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





CTask Cue

7

Transition Cue

6

1

Task Cue

Transition Cue

9

Magnitude Task

ParityTask

ParityTask

ParityTask

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Behavioral results

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

0

200

400

600

800

1000

1200

1400

Repeat Switch

Reaction Time in ms

Transition Cue

Task Cue

0

2

4

6

8

10

Repeat Switch

Error Rates in %

Transition Cue

Task Cue

2A 2B

Forstmann, Brass, Koch & von Cramon (submitted)

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fMRI results

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

2A

5.13.1

2BFrontolateral Gradient

0

0,05

0,1

0,15

0,2

0,25

Mid-MFG IFJ

(-44, 23, 27) (-35, -4, 32)

% Signal Change

*

Frontomedian Gradient

0

0,05

0,1

0,15

0,2

0,25

BA 8 pre-SMA/SMA

(-5, 17, 50) (1, 5, 53)

% Signal Change

*

Forstmann, Brass & von Cramon (submitted)

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The selection of task-relevant information

congruent incongruent neutral

red green xxxx

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Cue dimensions

magnitudetask

no TaskParitytask

form dimension

color dimension

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Cues

formdimension

colordimension

task A task B

congruent neutralincongruent congruent neutralincongruent

irrelevant

relevant

irrelevant

relevant

A AA

AB

B A NONO

NO NO

A AA B BB

BB B

A B

A B

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7


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Design

Instruction 1 warm up trial + 32 experimental trials + 4 null-events

Block

Block order

formcolor

formcolor

formcolor

formcolor

formcolor

formcolor

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Behavioral results

Brass & von Cramon (submitted)

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Possible contrasts

a) Incongruent/congruent (bivalent) versus neutral (univalent)

• selection of task-relevant context

b) Incongruent versus congruent

• selection of conflicting task representations

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neu con incon

neu con incon

Incongruent/congruent vs. neutral

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Conclusions

• Cortical areas more anterior in the prefronal cortex come

into play, whenever the information in the environment does

not directly indicate the relevant task-set.

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General conclusions

• The IFJ and the IPS play a crucial role in task preparation.

• Activation in the IFJ precedes activation in the IPS.

• Whenever the cue does not directly indicate which task to

execute, activation shifts anterior in the prefrontal cortex.

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The IFJ at the junction of three cortical domains

pre

mo

tor

do

mai

n

premotor domain• task-rules are an abstraction from stimulus-repsonse rules

language

domain

language domain• task-rules are represented in an abstract language-like formatpre

fronta

l dom

ain

prefrontal domain• task-rules are required for high-order cognitive control

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Dove et al. (2000)

If + left hand, if + right hand

Basis Taskfrequent

Critical Taskseldom

Response

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Dove et al. (2000)

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Fast versus slow responses in the long CTI


IFJ

CTI

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Fast versus slow responses in the long CTI


IFJ

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Cue-target versus cue-only


IFJ

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(1) Task-switching

Participants have to alternate between different task-sets

(2) Stroop interference task

A relevant but non-dominant stimulus dimension has to be

enforced against a irrelevant but dominant stimulus dimension.

(3) Verbal n-back task

Information have to be coordinated in working memory.

Paradigms on cognitive control

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Results of within-subject comparison

Overlap of activations in Stroop, task-switching and n-back

Derrfuss, Brass & von Cramon (submitted)

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Who comes first?

-2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C -2.5+2.5µV0.400 .. 0.520 s

-0.20.20.40.60.8

-5.0-2.5 2.55.0

s

µV

FCz

-2.5 2.5





C

33

cueswitch

3333

meaningswitch

trigger

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magnitudetask

parity task

color form color form

inconconneu inconconneuinconconneu inconconneu

inconconneu inconconneu inconconneu inconconneu

magnitudetask

parity task

W Max Planck Institute for Human Cognitive and Brain Sciences The role of the posterior prefrontal...

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