Irrational Economic Decision Making in Schizophrenia:

Evidence from the Ultimatum GameEvidence from the Ultimatum GameKorean Neuropsychiatric Association

2008.10.23, 03:25p.m.

Kyongsik Yun, Ph.D. CandidateKyongsik Yun, Ph.D. CandidateBio and Brain Engineering

KAISTyunks@kaist.edu

Questions to be asked• Is the Ultimatum game behavior of schizophrenia

different from that of normal controls?

• Does time frequency analysis of EEGs show impaired decision making in schizophrenia?

• Does phase synchronization of EEGs show impaired decision making in schizophrenia?

2

3

What are the temporal dynamics of social interaction?

proposer responder

4

What are the temporal dynamics of social interaction?

proposer responder

1. Make an offer: 9:1(send emotional cue)(send emotional cue)Reward anticipation (NAcc)

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What are the temporal dynamics of social interaction?

proposer responder

1. Make an offer: 9:1(send emotional cue) 2. Conflict btwn emotion & cognition

ACC, Ins, dlPFC activation (interaction)

responder

(send emotional cue)Reward anticipation (NAcc)

ACC, Ins, dlPFC activation (interaction)

6

What are the temporal dynamics of social interaction?

proposer responder

1. Make an offer: 9:1(send emotional cue) 2. Conflict btwn emotion & cognition

ACC, Ins, dlPFC activation (interaction)

responderresponder

(send emotional cue)Reward anticipation (NAcc)

ACC, Ins, dlPFC activation (interaction)3. Make a decision (reject: Ins)

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What are the temporal dynamics of social interaction?

proposer responder

1. Make an offer: 9:1(send emotional cue) 2. Conflict btwn emotion & cognition

ACC, Ins, dlPFC activation (interaction)

responderresponderproposer

(send emotional cue)Reward anticipation (NAcc)

ACC, Ins, dlPFC activation (interaction)

4. Reward prediction error

3. Make a decision (reject: Ins)

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Previous studies:

emotion vs. cognition

Sanfey et al. Science, 2003 9

What are the neural mechanisms of human decision making in the context of emotion and cognition?

Anterior dlPFC Anterior insula

dlPFC

ACC10

Time line for a single round of the Ultimatum Game

Subject decides

6 sec 6 sec 6 sec x sec 6 sec

+ He gets $9You get $1 Accept Reject He gets $0

You get $0

x: Time continues until the subject decides.

RevealFixation

RevealPartner

RevealOffer

RevealOptions

RevealOutcome

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Behavioral results from the Ultimatum Game

80

100

Schizophrenic

Control

20

40

60

Ac

cep

tan

ce r

ate

s (

%)

*

5:5 7:3 8:2 9:1

0

Offer

These are the offer acceptance rates averaged over all trials. Each of schizophrenia patients and normal controls saw three $5:$5 offers, two $7:$3 offers, two $8:$2 offers, and three $9:$1 offers from human partners (10 offers in total). 12

No difference between schizophrenia and controls was found in total earnings and reaction times.

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Group average of induced spectral power for all electrodesschizo

Overall power is decreased in schizo.Especially when accepting the offer -> fairness valuation deficiency

normal

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Topography of event related spectral power for each condition

Schizo accept

Normal accept

Schizo reject

-800~400ms

Normal reject

-400~0ms 0~400ms 400~800ms

SD

15

Group average of time series of event related spectral power for all electrodes and each decision in gamma

frequency range (30~50Hz)schizo

Lower overall power in schizo.Power change is not stable -> meaning?? regional communication is impaired.

normal

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Phase synchronization analysis

Lachaux et al. 1999 17

schizo

Long range

Group average of phase synchrony for all electrodes

normal

Long range synchronization and communication is impaired in schizoEspecially when accepting the offer -> fairness valuation deficiency

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Summary• Is the Ultimatum game behavior of schizophrenia

different from that of normal controls?– Yes. Abnormally accept. – Fairness valuation deficiency? Or economically rational?– Fairness valuation deficiency? Or economically rational?

• Does time frequency analysis of EEGs show impaired decision making in schizophrenia?– Yes. Lower overall power amplitude. – Especially when accepting the offer -> fairness valuation deficiency

• Does phase synchronization of EEGs show impaired decision making in schizophrenia?– Yes. Lower phase synchrony.– Especially when accepting the offer -> fairness valuation deficiency

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Acknowledgments

• Jaeseung Jeong, Ph.D.• Jaeseung Jeong, Ph.D.– Advisor, Brain Dynamics Lab, KAIST,

• Dongil Chung– Ph.D. candidate, Brain Dynamics Lab, KAIST

Yang Tae Kim, M.D.• Yang Tae Kim, M.D.– Bugok National Hospital

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