A Neuroeconomic Approach to Understanding Valuation of Risky Prospects

1. A Neuroeconomic Approach to Understanding Valuation of Risky Prospects Neal Hinvest University of Bath U.K.

2. What is neuroeconomics? ECONOMICS NEUROSCIENCE/ BEHAVIOURAL NEUROSCIENCE PSYCHOLOGY NEUROECONOMICS

3. Valuation of outcomes Go to another talk? • How we make the best decisions in the face of incomplete information? • Every outcome entails cost, therefore, all choices are economic decisions • All outcomes are processed (at or below conscious level) to maximise potential benefit taking into account potential loss • Valuations are occurring at every moment of our lives • Choice behaviour is based upon these valuations PUB! Pub? Listen to talk?

4. Valuation and the brain • To create valuations, “cold” and “hot” information must be integrated • The dopamine system has been identified as having a major role in reward processing • Important role in reward-prediction learning (Montague et al, 1996; O’Reilly et al, 1999; 2002) • The dopamine system projects through the striatum to the frontal cortex • Dorsal striatum = action selection and reward prediction • Ventral striatum = stimulus-response learning (for recent review see Hikosaka et al, 2008) • PFC = integration centre for top-down control (Miller & Cohen, 2001) • Damage to prefrontal regions leads to dysfunction of valuation mechanisms such as perseveration of a single action over time and incapacity to maintain a goal online • Plausible candidate for “valuation signal” is orbitofrontal cortex (Elliot et al. 2003; Knutson et al. 2001; O’Doherty et al. 2001; Bush et al., 2002)

5. What will be the impact of such research? • Identify mechanisms involved in specific aspects of human choice behaviour, and thus provide models of decision-making processes with biological validity • Answer key questions within economics and psychology (e.g. McClure et al, 2004) • Understand how possible alteration of the function of valuation mechanisms may underlie problematic behaviours (e.g. drug/gambling abuse)

6. Our research • Understanding neural substrates of valuation of risky prospects • Present potential gains and potential losses • Participants actively ascribe a personal worth to the prospect • Functional Magnetic Resonance Imaging (fMRI)

7. Results – potential reward • Valuation of potential rewards is associated with increased activity within bilateral OFC • Activation also measured in fronto-parieto-occipito networks P < .001 (uncorrected)

8. Results – potential loss • Valuation of potential losses is associated with activity in medial frontal regions extending from ventral OFC through VMPFC to dorso-medial PFC • Activity also measured in fronto-parieto-occipto networks P < .001 (uncorrected) P < .001 (uncorrected)

9. Conclusions • Increased evidence for OFC as having a major role in valuation • Possible source of signal integration • Suggestion of spatiotopic role of OFC in reward/loss processing (Elliot et al, 2000 ; Ursu et al, 2005; O’Doherty et al, 2003: medial = reward, lateral = loss)

10. Evidence for altered function of OFC in psychiatric samples • Pathological gamblers and drug abusers exhibit evidence of biased valuation mechanisms that place larger worth on addiction-related cues • This has been associated with dysfunction within dopamine-fed systems, most importantly, the prefrontal cortex • Presented substance abusers and pathological gamblers with a delay discounting task • Outcomes are presented for 3s, then participant is free to choose

11. Results • Drug abusers and pathological gamblers exhibit hyper-activation of a similar region of lateral dorsal OFC compared to controls when evaluating outcomes • This occurred even though there were no significant differences in choice behaviour • Represents existence of increased neural ‘effort’ to maintain behaviour at comparable levels to non-addicted groups (Padula et al, 2007)? Pathological gamblers Substance abusers

12. Conclusions • Increased evidence for role of OFC in valuation of risky outcomes • Possible existence of two overlapping systems for valuation of potential rewards and potential losses • Evidence for altered function of OFC in addiction-disordered groups (underlie biased valuations?)

13. University of Bath Alan Lewis John Cullis University of Warwick Gemma Calvert University of Exeter Tim Hodgson University of Oxford Rob Rogers University of Manchester Ian Anderson Rebecca Elliott Shane McKie Acknowledgements