Study 1:

1. Are All Rewards Created Equal? An fMRI Study Comparing Different Reward Types Hedy Kober, Samuel Gershman, Kevin N. Ochsner, & Tor D. Wager Department of Psychology, Columbia University SCAN Unit Dept. of Psychology 1190 Amsterdam Ave. 406 Schermerhorn Hall New York, NY 10027 Download this poster: http://www.columbia.edu/cu/psychology/tor/ www.scan.psych.columbia.edu Introduction • Scanning parameters: • 24 4mm slices on 1.5T GE Scanner. • TR: 2 seconds. • Pre-processing and RE analysis: FSL, SPM2, and robust regression at the 2nd level (Wager et al., 2005). Brain Imaging Results • Experimental work in animals and in humans has identified numerous neural structures involved in appetitive processes. • It has been shown that different types of appetitive cues (food, faces, money, pleasant odors) activate various subsets of this “reward system.” • Across experiments, little attention has been given to the importance of the type of reward used in each study. • Therefore, the extent to which reward-processing is domain-general or stimulus-specific is not yet clear. Question 2: Which areas are sensitive to variations in the desirability of rewards? To address this questions we performed two analyses: Question 1: Do different rewards activate common or distinct neural mechanisms? To address this questions we performed two analyses: Behavioral Results (manipulation check) • We compared activations in Reward Type > Rest (RT > R) contrasts in subcortical structural ROIs for regions shown to respond to rewards in previous studies. • We compared activations in High > Low (H>L) contrasts in subcortical structural ROIs for regions shown to respond to rewards in previous studies. • Post-scan ratings of stimuli show High>Medium>Low (F=29.78, p>.05). Nucleus Accumbens (left ventral) Nucleus Accumbens (right ventral) Nucleus Accumbens (left ventral) Nucleus Accumbens (right ventral) The Present Study * * p=.09 p=.06 * * * * * * p=.07 p=.09 p=.06 • The present study sought to determine whether reward representations depends upon common or distinct neural systems by varying: • 1. The type of reward presented. • The desirability of the reward, within of each reward type. T > R Activity H > L Activity H > L Activity T > R Activity * Face Face Face Money Money Face Food Food Money Food Food Money Food Faces Money Nucleus Accumbens (right dorsal) Nucleus Accumbens (left dorsal) Nucleus Accumbens (right dorsal) Nucleus Accumbens (left dorsal) Summary & Conclusions Design * * • Study 1: • 23 Ss viewed 265 pictures of food, attractive faces, symbols indicating monetary gains, and neutral objects. • Stimuli were rated on 14 dimensions including valence, arousal, desirability, interest, etc. • Ratings were subjected to Principal Components Analysis. two main components emerged – desirability (valence) and arousal. • Rewards were idiosyncratic; Ss had clear preferences for certain rewards, that differed across participants. • Using component scores we selected – for each subject – stimuli that were highly desirable for that individual, yet were matched in desirability across all subjects. • Pre-Screening for Study 2: • 52 new Ss rated stimuli as in the study 1. • For 18 participants, we selected stimulus sets of faces, foods, and monetary gain values matched for valence (desirability) for that participant. Arousal did not differ across types. • fMRI Participants: 9 male and 9 female undergraduate volunteers. • Stimuli: 45 individually chosen (yet controlled) pictures: • 15 Food • 15 Faces • 15 Money • Each presented twice, for a total of 90 trials. • Trial Event Structure: • Purpose: 1) Separate fMRI activity to pictures and rating; 2) Keep subjects engaged; 3) Ratings provide manipulation check. • Question 1: Do different rewards activate common or distinct neural mechanisms? • Answer 1:Reward processing depend on both common and unique mechanisms. • The Ventral Anterior Insula (vAI) and lateral Orbitofrontal Cortex (OFC) were similarly activated by all reward types, regardless of the level of desirability, paralleling the equity in reported desirability across the various rewards. • Other areas such as the Hypothalamus, Ventral Tegmental Area (VTA) and other limbic regions. showed reward-specific patterns of activation • VTA is significantly more active for faces than for money, and more active for food than for money. • Hypothalamus is more active for faces than for food. • Question 2: Which areas are sensitive to variations in the desirability of rewards? • Answer 2:Regions sensitive to reward desirability were specific to each stimulus type. • Very little overlap in regions sensitive to H>L. • Sub-clusters within Nucleus Accumbens (Nacc) seem to modulate response for food more than for money or faces. • Subregions in OFC sensitive to reward desirability for money and faces. • These findings raise questions about whether activity in the Nacc and other limbic regions represent motivational value in a domain-general manner. • Prospects & Promise • FIR analyses may reveal differences in shape of hemodynamic response across reward type/levels of desirability. • Individual differences may further shed light on differential sensitivity to reward types across participants. • Acknowledgements • The authors thank NSF for Graduate Research Fellowship to the first author, and NIDA for grant 1R01-DA022541-01 to Kevin N. Ochsner. H > L Activity H > L Activity T > R Activity T > R Activity Face Food Money Food Face Face Money Money Food Face Money Food Hypothalamus Ventral Tegmental Area Hypothalamus Ventral Tegmental Area P=.07 p=.06 * H > L Activity H > L Activity T > R Activity T > R Activity Food Face Money Face Face Money Money Food Food Food Face Money We masked the H>L activation maps within each reward types by areas associated with emotional experience We masked the RT>R activation maps for each of the three reward types by areas associated with emotional experience (Wager, T. D., & Feldman Barrett, L., in press.) (Wager, T. D., & Feldman Barrett, L., in press.) 5 High 5 Medium 5 Low Ventral Anterior Insula (peri-piriform) Insula MPFC VMPFC Lateral OFC (in each) Lateral OFC Ventral Anterior Insula Cerebellum Cerebellum Brain Stem Thalamus On Screen + + Type 1: Free Viewing + Anterior Insula Caudate DMPFC MPFC DMPFC Jittered ITI Delay Reward Cue 66% of trials Time Line ~ 5 secs 4 secs 16 secs Posterior Cingulate Ventral Striatum Hypothalamus + Q1 Q2 + On Screen Money + Type 2: View + Rate Overlap of Two Faces Overlap of All Jittered ITI Reward Cue Jittered Delay Jittered Q1 Jittered Q2 33% of trials Food ~ 5 sec ~6 secs Time Line 4 secs ~ 9 secs