Bio

Academic Appointments


Research & Scholarship

Current Research and Scholarly Interests


My lab and I seek to elucidate the neural basis of emotion (affective neuroscience), and explore implications for decision-making (neuroeconomics) and psychopathology (neurophenomics).

Teaching

2013-14 Courses


Graduate and Fellowship Programs


Publications

Journal Articles


  • Affective traits link to reliable neural markers of incentive anticipation. NeuroImage Wu, C. C., Samanez-Larkin, G. R., Katovich, K., Knutson, B. 2014; 84: 279-289

    Abstract

    While theorists have speculated that different affective traits are linked to reliable brain activity during anticipation of gains and losses, few have directly tested this prediction. We examined these associations in a community sample of healthy human adults (n=52) as they played a Monetary Incentive Delay task while undergoing functional magnetic resonance imaging (FMRI). Factor analysis of personality measures revealed that subjects independently varied in trait Positive Arousal and trait Negative Arousal. In a subsample (n=14) retested over 2.5years later, left nucleus accumbens (NAcc) activity during anticipation of large gains (+$5.00) and right anterior insula activity during anticipation of large losses (-$5.00) showed significant test-retest reliability (intraclass correlations>0.50, p's<0.01). In the full sample (n=52), trait Positive Arousal correlated with individual differences in left NAcc activity during anticipation of large gains, while trait Negative Arousal correlated with individual differences in right anterior insula activity during anticipation of large losses. Associations of affective traits with neural activity were not attributable to the influence of other potential confounds (including sex, age, wealth, and motion). Together, these results demonstrate selective links between distinct affective traits and reliably-elicited activity in neural circuits associated with anticipation of gain versus loss. The findings thus reveal neural markers for affective dimensions of healthy personality, and potentially for related psychiatric symptoms.

    View details for DOI 10.1016/j.neuroimage.2013.08.055

    View details for PubMedID 24001457

  • Interpretable whole-brain prediction analysis with GraphNet NEUROIMAGE Grosenick, L., Klingenberg, B., Katovich, K., Knutson, B., Taylor, J. E. 2013; 72: 304-321

    Abstract

    Multivariate machine learning methods are increasingly used to analyze neuroimaging data, often replacing more traditional "mass univariate" techniques that fit data one voxel at a time. In the functional magnetic resonance imaging (fMRI) literature, this has led to broad application of "off-the-shelf" classification and regression methods. These generic approaches allow investigators to use ready-made algorithms to accurately decode perceptual, cognitive, or behavioral states from distributed patterns of neural activity. However, when applied to correlated whole-brain fMRI data these methods suffer from coefficient instability, are sensitive to outliers, and yield dense solutions that are hard to interpret without arbitrary thresholding. Here, we develop variants of the Graph-constrained Elastic-Net (GraphNet), a fast, whole-brain regression and classification method developed for spatially and temporally correlated data that automatically yields interpretable coefficient maps (Grosenick et al., 2009b). GraphNet methods yield sparse but structured solutions by combining structured graph constraints (based on knowledge about coefficient smoothness or connectivity) with a global sparsity-inducing prior that automatically selects important variables. Because GraphNet methods can efficiently fit regression or classification models to whole-brain, multiple time-point data sets and enhance classification accuracy relative to volume-of-interest (VOI) approaches, they eliminate the need for inherently biased VOI analyses and allow whole-brain fitting without the multiple comparison problems that plague mass univariate and roaming VOI ("searchlight") methods. As fMRI data are unlikely to be normally distributed, we (1) extend GraphNet to include robust loss functions that confer insensitivity to outliers, (2) equip them with "adaptive" penalties that asymptotically guarantee correct variable selection, and (3) develop a novel sparse structured Support Vector GraphNet classifier (SVGN). When applied to previously published data (Knutson et al., 2007), these efficient whole-brain methods significantly improved classification accuracy over previously reported VOI-based analyses on the same data (Grosenick et al., 2008; Knutson et al., 2007) while discovering task-related regions not documented in the original VOI approach. Critically, GraphNet estimates fit to the Knutson et al. (2007) data generalize well to out-of-sample data collected more than three years later on the same task but with different subjects and stimuli (Karmarkar et al., submitted for publication). By enabling robust and efficient selection of important voxels from whole-brain data taken over multiple time points (>100,000 "features"), these methods enable data-driven selection of brain areas that accurately predict single-trial behavior within and across individuals.

    View details for DOI 10.1016/j.neuroimage.2012.12.062

    View details for Web of Science ID 000317166800030

    View details for PubMedID 23298747

  • Spatial smoothing systematically biases the localization of reward-related brain activity NEUROIMAGE Sacchet, M. D., Knutson, B. 2013; 66: 270-277
  • Serotonergic Genotypes, Neuroticism, and Financial Choices PLOS ONE Kuhnen, C. M., Samanez-Larkin, G. R., Knutson, B. 2013; 8 (1)

    Abstract

    Life financial outcomes carry a significant heritable component, but the mechanisms by which genes influence financial choices remain unclear. Focusing on a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR), we found that individuals possessing the short allele of this gene invested less in equities, were less engaged in actively making investment decisions, and had fewer credit lines. Short allele carriers also showed higher levels of the personality trait neuroticism, despite not differing from others with respect to cognitive skills, education, or wealth. Mediation analysis suggested that the presence of the 5-HTTLPR short allele decreased real life measures of financial risk taking through its influence on neuroticism. These findings show that 5-HTTLPR short allele carriers avoid risky and complex financial choices due to negative emotional reactions, and have implications for understanding and managing individual differences in financial choice.

    View details for DOI 10.1371/journal.pone.0054632

    View details for Web of Science ID 000315563800059

    View details for PubMedID 23382929

  • Frontostriatal White Matter Integrity Mediates Adult Age Differences in Probabilistic Reward Learning JOURNAL OF NEUROSCIENCE Samanez-Larkin, G. R., Levens, S. M., Perry, L. M., Dougherty, R. F., Knutson, B. 2012; 32 (15): 5333-5337

    Abstract

    Frontostriatal circuits have been implicated in reward learning, and emerging findings suggest that frontal white matter structural integrity and probabilistic reward learning are reduced in older age. This cross-sectional study examined whether age differences in frontostriatal white matter integrity could account for age differences in reward learning in a community life span sample of human adults. By combining diffusion tensor imaging with a probabilistic reward learning task, we found that older age was associated with decreased reward learning and decreased white matter integrity in specific pathways running from the thalamus to the medial prefrontal cortex and from the medial prefrontal cortex to the ventral striatum. Further, white matter integrity in these thalamocorticostriatal paths could statistically account for age differences in learning. These findings suggest that the integrity of frontostriatal white matter pathways critically supports reward learning. The findings also raise the possibility that interventions that bolster frontostriatal integrity might improve reward learning and decision making.

    View details for DOI 10.1523/JNEUROSCI.5756-11.2012

    View details for Web of Science ID 000302793500031

    View details for PubMedID 22496578

  • Toward an affective neuroscience account of financial risk taking. Frontiers in neuroscience Wu, C. C., Sacchet, M. D., Knutson, B. 2012; 6: 159-?

    Abstract

    To explain human financial risk taking, economic, and finance theories typically refer to the mathematical properties of financial options, whereas psychological theories have emphasized the influence of emotion and cognition on choice. From a neuroscience perspective, choice emanates from a dynamic multicomponential process. Recent technological advances in neuroimaging have made it possible for researchers to separately visualize perceptual input, intermediate processing, and motor output. An affective neuroscience account of financial risk taking thus might illuminate affective mediators that bridge the gap between statistical input and choice output. To test this hypothesis, we conducted a quantitative meta-analysis (via activation likelihood estimate or ALE) of functional magnetic resonance imaging experiments that focused on neural responses to financial options with varying statistical moments (i.e., mean, variance, skewness). Results suggested that different statistical moments elicit both common and distinct patterns of neural activity. Across studies, high versus low mean had the highest probability of increasing ventral striatal activity, but high versus low variance had the highest probability of increasing anterior insula activity. Further, high versus low skewness had the highest probability of increasing ventral striatal activity. Since ventral striatal activity has been associated with positive aroused affect (e.g., excitement), whereas anterior insular activity has been associated with negative aroused affect (e.g., anxiety) or general arousal, these findings are consistent with the notion that statistical input influences choice output by eliciting anticipatory affect. The findings also imply that neural activity can be used to predict financial risk taking - both when it conforms to and violates traditional models of choice.

    View details for DOI 10.3389/fnins.2012.00159

    View details for PubMedID 23129993

  • Spatial smoothing systematically biases the localization of reward-related brain activity. NeuroImage Sacchet, M. D., Knutson, B. 2012; 66C: 270-277

    Abstract

    Neuroimaging methods with enhanced spatial resolution such as functional magnetic resonance imaging (FMRI) suggest that the subcortical striatum plays a critical role in human reward processing. Analysis of FMRI data requires several preprocessing steps, some of which entail tradeoffs. For instance, while spatial smoothing can enhance statistical power, it may also bias localization towards regions that contain more gray than white matter. In a meta-analysis and reanalysis of an existing dataset, we sought to determine whether spatial smoothing could systematically bias the spatial localization of foci related to reward anticipation in the nucleus accumbens (NAcc). An activation likelihood estimate (ALE) meta-analysis revealed that peak ventral striatal ALE foci for studies that used smaller spatial smoothing kernels (i.e. <6mm FWHM) were more anterior than those identified for studies that used larger kernels (i.e. >7mm FWHM). Additionally, subtraction analysis of findings for studies that used smaller versus larger smoothing kernels revealed a significant cluster of differential activity in the left relatively anterior NAcc (Talairach coordinates: -10, 9, -1). A second meta-analysis revealed that larger smoothing kernels were correlated with more posterior localizations of NAcc activation foci (p<0.015), but revealed no significant associations with other potentially relevant parameters (including voxel volume, magnet strength, and publication date). Finally, repeated analysis of a representative dataset processed at different smoothing kernels (i.e., 0-12mm) also indicated that smoothing systematically yielded more posterior activation foci in the NAcc (p<0.005). Taken together, these findings indicate that spatial smoothing can systematically bias the spatial localization of striatal activity. These findings have implications both for historical interpretation of past findings related to reward processing and for the analysis of future studies.

    View details for PubMedID 23110886

  • Gain and Loss Learning Differentially Contribute to Life Financial Outcomes PLOS ONE Knutson, B., Samanez-Larkin, G. R., Kuhnen, C. M. 2011; 6 (9)

    Abstract

    Emerging findings imply that distinct neurobehavioral systems process gains and losses. This study investigated whether individual differences in gain learning and loss learning might contribute to different life financial outcomes (i.e., assets versus debt). In a community sample of healthy adults (n?=?75), rapid learners had smaller debt-to-asset ratios overall. More specific analyses, however, revealed that those who learned rapidly about gains had more assets, while those who learned rapidly about losses had less debt. These distinct associations remained strong even after controlling for potential cognitive (e.g., intelligence, memory, and risk preferences) and socioeconomic (e.g., age, sex, ethnicity, income, education) confounds. Self-reported measures of assets and debt were additionally validated with credit report data in a subset of subjects. These findings support the notion that different gain and loss learning systems may exert a cumulative influence on distinct life financial outcomes.

    View details for DOI 10.1371/journal.pone.0024390

    View details for Web of Science ID 000294689200041

    View details for PubMedID 21915320

  • The Influence of Affect on Beliefs, Preferences, and Financial Decisions JOURNAL OF FINANCIAL AND QUANTITATIVE ANALYSIS Kuhnen, C. M., Knutson, B. 2011; 46 (3): 605-626
  • Expected value information improves financial risk taking across the adult life span SOCIAL COGNITIVE AND AFFECTIVE NEUROSCIENCE Samanez-Larkin, G. R., Wagner, A. D., Knutson, B. 2011; 6 (2): 207-217

    Abstract

    When making decisions, individuals must often compensate for cognitive limitations, particularly in the face of advanced age. Recent findings suggest that age-related variability in striatal activity may increase financial risk-taking mistakes in older adults. In two studies, we sought to further characterize neural contributions to optimal financial risk taking and to determine whether decision aids could improve financial risk taking. In Study 1, neuroimaging analyses revealed that individuals whose mesolimbic activation correlated with the expected value estimates of a rational actor made more optimal financial decisions. In Study 2, presentation of expected value information improved decision making in both younger and older adults, but the addition of a distracting secondary task had little impact on decision quality. Remarkably, provision of expected value information improved the performance of older adults to match that of younger adults at baseline. These findings are consistent with the notion that mesolimbic circuits play a critical role in optimal choice, and imply that providing simplified information about expected value may improve financial risk taking across the adult life span.

    View details for DOI 10.1093/scan/nsq043

    View details for Web of Science ID 000291543100006

    View details for PubMedID 20501485

  • The Affective Impact of Financial Skewness on Neural Activity and Choice PLOS ONE Wu, C. C., Bossaerts, P., Knutson, B. 2011; 6 (2)

    Abstract

    Few finance theories consider the influence of "skewness" (or large and asymmetric but unlikely outcomes) on financial choice. We investigated the impact of skewed gambles on subjects' neural activity, self-reported affective responses, and subsequent preferences using functional magnetic resonance imaging (FMRI). Neurally, skewed gambles elicited more anterior insula activation than symmetric gambles equated for expected value and variance, and positively skewed gambles also specifically elicited more nucleus accumbens (NAcc) activation than negatively skewed gambles. Affectively, positively skewed gambles elicited more positive arousal and negatively skewed gambles elicited more negative arousal than symmetric gambles equated for expected value and variance. Subjects also preferred positively skewed gambles more, but negatively skewed gambles less than symmetric gambles of equal expected value. Individual differences in both NAcc activity and positive arousal predicted preferences for positively skewed gambles. These findings support an anticipatory affect account in which statistical properties of gambles--including skewness--can influence neural activity, affective responses, and ultimately, choice.

    View details for DOI 10.1371/journal.pone.0016838

    View details for Web of Science ID 000287369200010

    View details for PubMedID 21347239

  • When Giving Is Good: Ventromedial Prefrontal Cortex Activation for Others' Intentions NEURON Cooper, J. C., Kreps, T. A., Wiebe, T., Pirkl, T., Knutson, B. 2010; 67 (3): 511-521

    Abstract

    In social decision-making, people care both about others' outcomes and their intentions to help or harm. How the brain integrates representations of others' intentions with their outcomes, however, is unknown. In this study, participants inferred others' decisions in an economic game during functional magnetic resonance imaging. When the game was described in terms of donations, ventromedial prefrontal cortex (VMPFC) activation increased for inferring generous play and decreased for inferring selfish play. When the game was described in terms of individual savings, however, VMPFC activation did not distinguish between strategies. Distinct medial prefrontal regions also encoded consistency with situational norms. A separate network, including right temporoparietal junction and parahippocampal gyrus, was more activated for inferential errors in the donation than in the savings condition. These results demonstrate that neural responses to others' generosity or selfishness depend not only on their actions but also on their perceived intentions.

    View details for DOI 10.1016/j.neuron.2010.06.030

    View details for Web of Science ID 000280942900017

    View details for PubMedID 20696386

  • Variability in Nucleus Accumbens Activity Mediates Age-Related Suboptimal Financial Risk Taking JOURNAL OF NEUROSCIENCE Samanez-Larkin, G. R., Kuhnen, C. M., Yoo, D. J., Knutson, B. 2010; 30 (4): 1426-1434

    Abstract

    As human life expectancy continues to rise, financial decisions of aging investors may have an increasing impact on the global economy. In this study, we examined age differences in financial decisions across the adult life span by combining functional neuroimaging with a dynamic financial investment task. During the task, older adults made more suboptimal choices than younger adults when choosing risky assets. This age-related effect was mediated by a neural measure of temporal variability in nucleus accumbens activity. These findings reveal a novel neural mechanism by which aging may disrupt rational financial choice.

    View details for DOI 10.1523/JNEUROSCI.4902-09.2010

    View details for Web of Science ID 000274050000024

    View details for PubMedID 20107069

  • Available alternative incentives modulate anticipatory nucleus accumbens activation SOCIAL COGNITIVE AND AFFECTIVE NEUROSCIENCE Cooper, J. C., Hollon, N. G., Wimmer, G. E., Knutson, B. 2009; 4 (4): 409-416

    Abstract

    A reward or punishment can seem better or worse depending on what else might have happened. Little is known, however, about how neural representations of an anticipated incentive might be influenced by the available alternatives. We used event-related FMRI to investigate the activation in the nucleus accumbens (NAcc), while we varied the available alternative incentives in a monetary incentive delay task. Some task blocks included only uncertain gains and losses; others included the same uncertain gains and losses intermixed with certain gains and losses. The availability of certain gains and losses increased NAcc activation for uncertain losses and decreased the difference between uncertain gains and losses. We suggest that this pattern of activation can result from reference point changes across blocks, and that the worst available loss may serve as an important anchor for NAcc activation. These findings imply that NAcc activation represents anticipated incentive value relative to the current context of available alternative gains and losses.

    View details for DOI 10.1093/scan/nsp031

    View details for Web of Science ID 000273231000010

    View details for PubMedID 19843618

  • Correction. "Affect dynamics, affective forecasting, and aging". Emotion Nielsen, L., Knutson, B., Carstensen, L. L. 2009; 9 (5): ii-?

    Abstract

    Reports an error in "Affect dynamics, affective forecasting, and aging" by Lisbeth Nielsen, Brian Knutson and Laura L. Carstensen (Emotion, 2008[Jun], Vol 8[3], 318-330). The first author of the article was listed as being affiliated with both the National Institute on Aging and the Department of Psychology, Stanford University. Dr. Nielsen would like to clarify that the research for this article was conducted while she was a postdoctoral fellow at Stanford University; her current affiliation is only with the National Institute on Aging. The copyright notice should also have been listed as "In the Public Domain." (The following abstract of the original article appeared in record 2008-06717-002.) [Correction Notice: The same erratum for this article was reported in Vol 8(5) of Emotion (see record 2008-13989-013).] Affective forecasting, experienced affect, and recalled affect were compared in younger and older adults during a task in which participants worked to win and avoid losing small monetary sums. Dynamic changes in affect were measured along valence and arousal dimensions, with probes during both anticipatory and consummatory task phases. Older and younger adults displayed distinct patterns of affect dynamics. Younger adults reported increased negative arousal during loss anticipation and positive arousal during gain anticipation. In contrast, older adults reported increased positive arousal during gain anticipation but showed no increase in negative arousal on trials involving loss anticipation. Additionally, younger adults reported large increases in valence after avoiding an anticipated loss, but older adults did not. Younger, but not older, adults exhibited forecasting errors on the arousal dimension, underestimating increases in arousal during anticipation of gains and losses and overestimating increases in arousal in response to gain outcomes. Overall, the findings are consistent with a growing literature suggesting that older people experience less negative emotion than their younger counterparts and further suggest that they may better predict dynamic changes in affect.

    View details for DOI 10.1037/a0015739

    View details for PubMedID 19803581

  • Don't stop thinking about tomorrow: Individual differences in future self-continuity account for saving JUDGMENT AND DECISION MAKING Ersner-Hershfield, H., Garton, M. T., Ballard, K., Samanez-Larkin, G. R., Knutson, B. 2009; 4 (4): 280-286

    Abstract

    Some people find it more difficult to delay rewards than others. In three experiments, we tested a "future self-continuity" hypothesis that individual differences in the perception of one's present self as continuous with a future self would be associated with measures of saving in the laboratory and everyday life. Higher future self-continuity (assessed by a novel index) predicted reduced discounting of future rewards in a laboratory task, more matches in adjectival descriptions of present and future selves, and greater lifetime accumulation of financial assets (even after controlling for age and education). In addition to demonstrating the reliability and validity of the future self-continuity index, these findings are consistent with the notion that increased future self-continuity might promote saving for the future.

    View details for Web of Science ID 000267218800003

  • Dissociable neural representations of future reward magnitude and delay during temporal discounting NEUROIMAGE Ballard, K., Knutson, B. 2009; 45 (1): 143-150

    Abstract

    In temporal discounting, individuals often prefer smaller immediate rewards to larger delayed rewards, implying a trade off between the magnitude and delay of future rewards. While recent functional magnetic resonance imaging (fMRI) investigations of temporal discounting have generated conflicting findings, no studies have focused on whether distinct neural substrates respond to the magnitude and delay of future rewards. Combining a novel, temporally distributed discounting task with event-related fMRI, we found that while nucleus accumbens (NAcc), mesial prefrontal cortical (MPFC), and posterior cingulate cortical (PCC) activation positively correlated with future reward magnitude, dorsolateral prefrontal cortical (DLPFC) and posterior parietal cortical (PPC) activation negatively correlated with future reward delay. Further, more impulsive individuals showed diminished NAcc activation to the magnitude of future rewards and greater deactivations to delays of future rewards in the MPFC, DLPFC, and PPC. These findings suggest that while mesolimbic dopamine projection regions show greater sensitivity to the magnitude of future rewards, lateral cortical regions show greater (negative) sensitivity to the delay of future rewards, potentially reconciling different neural accounts of temporal discounting.

    View details for DOI 10.1016/j.neuroimage.2008.11.004

    View details for Web of Science ID 000263862900017

    View details for PubMedID 19071223

  • Saving for the future self: Neural measures of future self-continuity predict temporal discounting SOCIAL COGNITIVE AND AFFECTIVE NEUROSCIENCE Ersner-Hershfield, H., Wimmer, G. E., Knutson, B. 2009; 4 (1): 85-92

    Abstract

    Despite increases in the human life span, people have not increased their rate of saving. In a phenomenon known as 'temporal discounting', people value immediate gains over future gains. According to a future self-continuity hypothesis, individuals perceive and treat the future self differently from the present self, and so might fail to save for their future. Neuroimaging offers a novel means of testing this hypothesis, since previous research indicates that self- vs other-judgments elicit activation in the rostral anterior cingulate (rACC). Using event-related functional magnetic resonance imaging, we predicted and found not only individual differences in rACC activation while rating the current vs future self, but also that individual differences in current vs future self activation predicted temporal discounting assessed behaviorally a week after scanning. In addition to supporting the future self-continuity hypothesis, these findings hold implications for significant financial decisions, such as choosing whether to save for the future or spend in the present.

    View details for DOI 10.1093/scan/nsn042

    View details for Web of Science ID 000264398000009

    View details for PubMedID 19047075

  • Anticipatory affect: neural correlates and consequences for choice PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Knutson, B., Greer, S. M. 2008; 363 (1511): 3771-3786

    Abstract

    'Anticipatory affect' refers to emotional states that people experience while anticipating significant outcomes. Historically, technical limitations have made it difficult to determine whether anticipatory affect influences subsequent choice. Recent advances in the spatio-temporal resolution of functional magnetic resonance imaging, however, now allow researchers to visualize changes in neural activity seconds before choice occurs. We review evidence that activation in specific brain circuits changes during anticipation of monetary incentives, that this activation correlates with affective experience and that activity in these circuits may influence subsequent choice. Specifically, an activation likelihood estimate meta-analysis of cued response studies indicates that nucleus accumbens (NAcc) activation increases during gain anticipation relative to loss anticipation, while anterior insula activation increases during both loss and gain anticipation. Additionally, anticipatory NAcc activation correlates with self-reported positive arousal, whereas anterior insula activation correlates with both self-reported negative and positive arousal. Finally, NAcc activation precedes the purchase of desirable products and choice of high-risk gambles, whereas anterior insula activation precedes the rejection of overpriced products and choice of low-risk gambles. Together, these findings support a neurally plausible framework for understanding how anticipatory affect can influence choice.

    View details for DOI 10.1098/rstb.2008.0155

    View details for Web of Science ID 000260864600002

    View details for PubMedID 18829428

  • Interpretable Classifiers for fMRI Improve Prediction of Purchases IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING Grosenick, L., Greer, S., Knutson, B. 2008; 16 (6): 539-548

    Abstract

    Despite growing interest in applying machine learning to neuroimaging analyses, few studies have gone beyond classifying sensory input to directly predicting behavioral output. With spatial resolution on the order of millimeters and temporal resolution on the order of seconds, functional magnetic resonance imaging (fMRI) is a promising technology for such applications. However, fMRI data's low signal-to-noise ratio, high dimensionality, and extensive spatiotemporal correlations present formidable analytic challenges. Here, we apply different machine-learning algorithms to previously acquired data to examine the ability of fMRI activation in three regions-the nucleus accumbens (NAcc), medial prefrontal cortex (MPFC), and insula-to predict purchasing. Our goal was to improve spatiotemporal interpretability as well as classification accuracy. To this end, sparse penalized discriminant analysis (SPDA) enabled automatic selection of correlated variables, yielding interpretable models that generalized well to new data. Relative to logistic regression, linear discriminant analysis, and linear support vector machines, SPDA not only increased interpretability but also improved classification accuracy. SPDA promises to allow more precise inferences about when specific brain regions contribute to purchasing decisions. More broadly, this approach provides a general framework for using neuroimaging data to build interpretable models, including those that predict choice.

    View details for DOI 10.1109/TNSRE.2008.926701

    View details for Web of Science ID 000262557000004

    View details for PubMedID 19144586

  • Incentive-elicited striatal activation in adolescent children of alcoholics ADDICTION Bjork, J. M., Knutson, B., Hommer, D. W. 2008; 103 (8): 1308-1319

    Abstract

    Deficient recruitment of motivational circuitry by non-drug rewards has been postulated as a pre-morbid risk factor for substance dependence (SD). We tested whether parental alcoholism, which confers risk of SD, is correlated with altered recruitment of ventral striatum (VS) by non-drug rewards in adolescence.During functional magnetic resonance imaging, adolescent children of alcoholics (COA; age 12-16 years) with no psychiatric disorders (including substance abuse) and similarly aged children with no risk factors responded to targets to win or avoid losing $0, $0.20, $1, $5 or a variable amount (ranging from $0.20 to $5).In general, brain activation by either reward anticipation or outcome notification did not differ between COA and age/gender-matched controls. Cue-elicited reward anticipation activated portions of VS in both COA and controls. In nucleus accumbens (NAcc), signal change increased with anticipated reward magnitude (with intermediate recruitment by variable incentives) but not with loss magnitudes. Reward deliveries activated the NAcc and mesofrontal cortex in both COA and controls. Losses activated anterior insula bilaterally in both groups, with more extensive right anterior insula activation by losses in controls. NAcc signal change during anticipation of maximum rewards (relative to non-reward) correlated positively with both Brief Sensation-Seeking Scale scores and with self-reported excitement in response to maximum reward cues (relative to cues for non-reward).Among adolescents with no psychiatric disorders, incentive-elicited VS activation may relate more to individual differences in sensation-seeking personality than to presence of parental alcoholism alone. Future research could focus on adolescents with behavior disorders or additional risk factors.

    View details for DOI 10.1111/j.1360-0443.2008.02250.x

    View details for Web of Science ID 000257692800010

    View details for PubMedID 18851716

  • Neural antecedents of the endowment effect NEURON Knutson, B., Wimmer, G. E., Rick, S., Hollon, N. G., Prelec, D., Loewenstein, G. 2008; 58 (5): 814-822

    Abstract

    The "endowment effect" refers to the tendency to place greater value on items that one owns-an anomaly that violates the reference-independence assumption of rational choice theories. We investigated neural antecedents of the endowment effect in an event-related functional magnetic resonance imaging (fMRI) study. During scanning, 24 subjects considered six products paired with 18 different prices under buying, choosing, or selling conditions. Subjects showed greater nucleus accumbens (NAcc) activation for preferred products across buy and sell conditions combined, but greater mesial prefrontal cortex (MPFC) activation in response to low prices when buying versus selling. During selling, right insular activation for preferred products predicted individual differences in susceptibility to the endowment effect. These findings are consistent with a reference-dependent account in which ownership increases value by enhancing the salience of the possible loss of preferred products.

    View details for DOI 10.1016/j.neuron.2008.05.018

    View details for Web of Science ID 000256870800017

    View details for PubMedID 18549791

  • Affect dynamics, affective forecasting, and aging EMOTION Nielsen, L., Knutson, B., Carstensen, L. L. 2008; 8 (3): 318-330

    Abstract

    Affective forecasting, experienced affect, and recalled affect were compared in younger and older adults during a task in which participants worked to win and avoid losing small monetary sums. Dynamic changes in affect were measured along valence and arousal dimensions, with probes during both anticipatory and consummatory task phases. Older and younger adults displayed distinct patterns of affect dynamics. Younger adults reported increased negative arousal during loss anticipation and positive arousal during gain anticipation. In contrast, older adults reported increased positive arousal during gain anticipation but showed no increase in negative arousal on trials involving loss anticipation. Additionally, younger adults reported large increases in valence after avoiding an anticipated loss, but older adults did not. Younger, but not older, adults exhibited forecasting errors on the arousal dimension, underestimating increases in arousal during anticipation of gains and losses and overestimating increases in arousal in response to gain outcomes. Overall, the findings are consistent with a growing literature suggesting that older people experience less negative emotion than their younger counterparts and further suggest that they may better predict dynamic changes in affect.

    View details for DOI 10.1037/1528-3542.8.3.318

    View details for Web of Science ID 000256512900002

    View details for PubMedID 18540748

  • Individual differences in insular sensitivity during loss anticipation predict avoidance learning PSYCHOLOGICAL SCIENCE Samanez-Larkin, G. R., Hollon, N. G., Carstensen, L. L., Knutson, B. 2008; 19 (4): 320-323

    Abstract

    The anterior insula has been implicated in both the experience and the anticipation of negative outcomes. Although individual differences in insular sensitivity have been associated with self-report measures of chronic anxiety, previous research has not examined whether individual differences in insular sensitivity predict learning to avoid aversive stimuli. In the present study, insular sensitivity was assessed as participants anticipated monetary losses while undergoing functional magnetic resonance imaging. We found that insular responsiveness to anticipated losses predicted participants' ability to learn to avoid losses (but not to approach gains) in a behavioral test several months later. These findings suggest that in addition to correlating with self-reported anxiety, heightened insular sensitivity may promote learning to avoid loss.

    View details for Web of Science ID 000254792000003

    View details for PubMedID 18399882

  • Neural responses to monetary incentives in major depression BIOLOGICAL PSYCHIATRY Knutson, B., Bhanji, J. P., Cooney, R. E., Atlas, L. Y., Gotlib, I. H. 2008; 63 (7): 686-692

    Abstract

    Reduced responsiveness to positive incentives is a central feature of Major Depressive Disorder (MDD). In the present study, we compared neural correlates of monetary incentive processing in unmedicated depressed participants and never-depressed control subjects.Fourteen currently depressed and 12 never-depressed participants underwent functional magnetic resonance imaging while participating in a monetary incentive delay task. During the task, participants were cued to anticipate and respond to a rapidly presented target to gain or avoid losing varying amounts of money.Depressed and never-depressed participants did not differ in nucleus accumbens (NAcc) activation or in affective or behavioral responses during gain anticipation. Depressed participants did, however, exhibit increasing anterior cingulate activation during anticipation of increasing gains, whereas never-depressed participants showed increasing anterior cingulate activation during anticipation of increasing loss. Depressed participants also showed reduced discrimination of gain versus nongain outcomes.The present findings indicate that although unmedicated depressed individuals have the capacity to experience positive arousal and recruit NAcc activation during gain anticipation, they also exhibit increased anterior cingulate cortex activation, suggestive of increased conflict during anticipation of gains, in addition to showing reduced discrimination of gain versus nongain outcomes.

    View details for DOI 10.1016/j.biopsych.2007.07.023

    View details for Web of Science ID 000254107100008

    View details for PubMedID 17916330

  • Nucleus accumbens activation mediates the influence of reward cues on financial risk taking NEUROREPORT Knutson, B., Wimmer, G. E., Kuhnen, C. M., Winkielman, P. 2008; 19 (5): 509-513

    Abstract

    In functional magnetic resonance imaging research, nucleus accumbens (NAcc) activation spontaneously increases before financial risk taking. As anticipation of diverse rewards can increase NAcc activation, even incidental reward cues may influence financial risk taking. Using event-related functional magnetic resonance imaging, we predicted and found that anticipation of viewing rewarding stimuli (erotic pictures for 15 heterosexual men) increased financial risk taking, and that this effect was partially mediated by increases in NAcc activation. These results are consistent with the notion that incidental reward cues influence financial risk taking by altering anticipatory affect, and so identify a neuropsychological mechanism that may underlie effective emotional appeals in financial, marketing, and political domains.

    View details for Web of Science ID 000254372100001

    View details for PubMedID 18388729

  • Valence and salience contribute to nucleus accumbens activation NEUROIMAGE Cooper, J. C., Knutson, B. 2008; 39 (1): 538-547

    Abstract

    Different accounts of nucleus accumbens (NAcc) function have emphasized its role in representing either valence or salience during incentive anticipation. In an event-related FMRI experiment, we independently manipulated valence and salience by cuing participants to anticipate certain and uncertain monetary gains and losses. NAcc activation correlated with both valence and salience. On trials with certain outcomes, NAcc activation increased for anticipated gains and decreased for anticipated losses. On trials with uncertain outcomes, NAcc activation increased for both anticipated gains and losses but did not differ between them. These findings suggest that NAcc activation separately represents both valence and salience, consistent with its hypothesized role in appetitive motivation.

    View details for DOI 10.1016/j.neuroimage.2007.08.009

    View details for Web of Science ID 000251406000048

    View details for PubMedID 17904386

  • Neural antecedents of financial decisions JOURNAL OF NEUROSCIENCE Knutson, B., Bossaerts, P. 2007; 27 (31): 8174-8177

    Abstract

    To explain investing decisions, financial theorists invoke two opposing metrics: expected reward and risk. Recent advances in the spatial and temporal resolution of brain imaging techniques enable investigators to visualize changes in neural activation before financial decisions. Research using these methods indicates that although the ventral striatum plays a role in representation of expected reward, the insula may play a more prominent role in the representation of expected risk. Accumulating evidence also suggests that antecedent neural activation in these regions can be used to predict upcoming financial decisions. These findings have implications for predicting choices and for building a physiologically constrained theory of decision-making.

    View details for DOI 10.1523/JNEUROSCI.1564-07.2007

    View details for Web of Science ID 000248502200006

    View details for PubMedID 17670962

  • Anticipation of monetary gain but not loss in healthy older adults NATURE NEUROSCIENCE Samanez-Larkin, G. R., Gibbs, S. E., Khanna, K., Nielsen, L., Carstensen, L. L., Knutson, B. 2007; 10 (6): 787-791

    Abstract

    Although global declines in structure have been documented in the aging human brain, little is known about the functional integrity of the striatum and prefrontal cortex in older adults during incentive processing. We used event-related functional magnetic resonance imaging to determine whether younger and older adults differed in both self-reported and neural responsiveness to anticipated monetary gains and losses. The present study provides evidence for intact striatal and insular activation during gain anticipation with age, but shows a relative reduction in activation during loss anticipation. These findings suggest that there is an asymmetry in the processing of gains and losses in older adults that may have implications for decision-making.

    View details for DOI 10.1038/nn1894

    View details for Web of Science ID 000246799800022

    View details for PubMedID 17468751

  • Affective influence on judgments and decisions: Moving towards core mechanisms REVIEW OF GENERAL PSYCHOLOGY Winkielman, P., Knutson, B., Paulus, M., Trujillo, J. L. 2007; 11 (2): 179-192
  • Linking nucleus accumbens dopamine and blood oxygenation PSYCHOPHARMACOLOGY Knutson, B., Gibbs, S. E. 2007; 191 (3): 813-822

    Abstract

    Animal research suggests that anticipation of reward can elicit dopamine release in the nucleus accumbens (NAcc). Human functional magnetic resonance imaging (FMRI) research further suggests that reward anticipation can increase local blood oxygen level dependent (BOLD) signal in the NAcc. However, the physiological relationship between dopamine release and BOLD signal increases in the NAcc has not yet been established.This review considers pharmacological MRI (phMRI) evidence for a directional relationship between NAcc dopamine release and BOLD signal, as well as implications for human psychopathological symptoms.Accumulating phMRI evidence supports a simple model in which NAcc dopamine release activates postsynaptic D1 receptors, which changes postsynaptic membrane potential, eventually increasing local BOLD signal. This continuing influence can change on a second-to-second basis.Dopamine release in the NAcc appears to increase local BOLD signal via agonism of postsynaptic D1 receptors. Such a physiological mechanism implies that FMRI may be used to track symptoms related to NAcc dopaminergic dysregulation in psychiatric disorders including schizophrenia and attention deficit/hyperactivity disorder.

    View details for DOI 10.1007/s00213-006-0686-7

    View details for Web of Science ID 000244691500032

    View details for PubMedID 17279377

  • Neural predictors of purchases NEURON Knutson, B., Rick, S., Wirnmer, G. E., Prelec, D., Loewenstein, G. 2007; 53 (1): 147-156

    Abstract

    Microeconomic theory maintains that purchases are driven by a combination of consumer preference and price. Using event-related fMRI, we investigated how people weigh these factors to make purchasing decisions. Consistent with neuroimaging evidence suggesting that distinct circuits anticipate gain and loss, product preference activated the nucleus accumbens (NAcc), while excessive prices activated the insula and deactivated the mesial prefrontal cortex (MPFC) prior to the purchase decision. Activity from each of these regions independently predicted immediately subsequent purchases above and beyond self-report variables. These findings suggest that activation of distinct neural circuits related to anticipatory affect precedes and supports consumers' purchasing decisions.

    View details for DOI 10.1016/j.neuron.2006.11.010

    View details for Web of Science ID 000245126500015

    View details for PubMedID 17196537

  • Splitting the difference - How does the brain code reward episodes? REWARD AND DECISION MAKING IN CORTICOBASAL GANGLIA NETWORKS Knutson, B., Wimmer, G. E. 2007; 1104: 54-69

    Abstract

    Animal research and human brain imaging findings suggest that reward processing involves distinct anticipation and outcome phases. Error terms in popular models of reward learning (such as the temporal difference [TD] model) do not distinguish between the updating of expectations in response to reward cues and outcomes. Thus, correlating a single error term with neural activation assumes recruitment of similar neural substrates at each update. Here, we split the error term to separately model reward prediction and prediction errors, and compare the fit of single versus split error terms to functional magnetic resonance imaging (FMRI) data acquired during a monetary incentive delay task. We speculate and find that while the nucleus accumbens computes gain prediction in response to cues, the mesial prefrontal cortex (MPFC) computes gain prediction errors in response to outcomes. In addition to offering a more comprehensive and anatomically situated view of reward processing, split error terms generate novel predictions about psychiatric symptoms and lesion-induced deficits.

    View details for DOI 10.1196/annals.1390.020

    View details for Web of Science ID 000248194800005

    View details for PubMedID 17416922

  • The lure of the unknown NEURON Knutson, B., Cooper, J. C. 2006; 51 (3): 280-282

    Abstract

    Using event-related fMRI, Bunzeck and Düzel show that midbrain regions putatively housing dopamine cell bodies activate more for novel pictures than for negative pictures, pictures requiring a motor response, or repeated pictures. These findings indicate that midbrain regions preferentially respond to novelty and suggest that novelty can serve as its own reward.

    View details for DOI 10.1016/j.neuron.2006.07.017

    View details for Web of Science ID 000239908800003

    View details for PubMedID 16880122

  • Cultural variation in affect valuation JOURNAL OF PERSONALITY AND SOCIAL PSYCHOLOGY Tsai, J. L., Knutson, B., Fung, H. H. 2006; 90 (2): 288-307

    Abstract

    The authors propose that how people want to feel ("ideal affect") differs from how they actually feel ("actual affect") and that cultural factors influence ideal more than actual affect. In 2 studies, controlling for actual affect, the authors found that European American (EA) and Asian American (AA) individuals value high-arousal positive affect (e.g., excitement) more than do Hong Kong Chinese (CH). On the other hand, CH and AA individuals value low-arousal positive affect (e.g., calm) more than do EA individuals. For all groups, the discrepancy between ideal and actual affect correlates with depression. These findings illustrate the distinctiveness of ideal and actual affect, show that culture influences ideal affect more than actual affect, and indicate that both play a role in mental health.

    View details for DOI 10.1037/0022-3514.90.2.288

    View details for Web of Science ID 000236445600007

    View details for PubMedID 16536652

  • The neural basis of financial risk taking NEURON Kuhnen, C. M., Knutson, B. 2005; 47 (5): 763-770

    Abstract

    Investors systematically deviate from rationality when making financial decisions, yet the mechanisms responsible for these deviations have not been identified. Using event-related fMRI, we examined whether anticipatory neural activity would predict optimal and suboptimal choices in a financial decision-making task. We characterized two types of deviations from the optimal investment strategy of a rational risk-neutral agent as risk-seeking mistakes and risk-aversion mistakes. Nucleus accumbens activation preceded risky choices as well as risk-seeking mistakes, while anterior insula activation preceded riskless choices as well as risk-aversion mistakes. These findings suggest that distinct neural circuits linked to anticipatory affect promote different types of financial choices and indicate that excessive activation of these circuits may lead to investing mistakes. Thus, consideration of anticipatory neural mechanisms may add predictive power to the rational actor model of economic decision making.

    View details for DOI 10.1016/j.neuron.2005.08.008

    View details for Web of Science ID 000231782700016

    View details for PubMedID 16129404

  • Functional magnetic resonance imaging of reward prediction CURRENT OPINION IN NEUROLOGY Knutson, B., Cooper, J. C. 2005; 18 (4): 411-417

    Abstract

    Technical and conceptual advances in functional magnetic resonance imaging now allow visualization of real-time changes in oxygenation of deep subcortical regions, leading to rapid advances in scientific characterization of the neural substrates that underlie reward prediction in humans.Neuroimaging research over the past year has focused on determining the necessary neural substrates for reward prediction.While the orbitofrontal cortex has long been implicated in modality-specific reward representation, the ventral striatum (particularly the nucleus accumbens) may play a role in modality-independent representations of predicted reward. On the other hand, the mesial prefrontal cortex appears to play a role in representing reward prediction error and the dorsal caudate in linking reward to behavior. Theoretically, future studies will need to establish the specificity of these responses to reward versus punishment and anticipation versus outcome. Clinically, current findings suggest that patients can predict reward without a prefrontal cortex, but should experience difficulty correcting their behavior when reward predictions are violated.

    View details for Web of Science ID 000231075100009

    View details for PubMedID 16003117

  • Distributed neural representation of expected value JOURNAL OF NEUROSCIENCE Knutson, B., Taylor, J., Kaufman, M., Peterson, R., Glover, G. 2005; 25 (19): 4806-4812

    Abstract

    Anticipated reward magnitude and probability comprise dual components of expected value (EV), a cornerstone of economic and psychological theory. However, the neural mechanisms that compute EV have not been characterized. Using event-related functional magnetic resonance imaging, we examined neural activation as subjects anticipated monetary gains and losses that varied in magnitude and probability. Group analyses indicated that, although the subcortical nucleus accumbens (NAcc) activated proportional to anticipated gain magnitude, the cortical mesial prefrontal cortex (MPFC) additionally activated according to anticipated gain probability. Individual difference analyses indicated that, although NAcc activation correlated with self-reported positive arousal, MPFC activation correlated with probability estimates. These findings suggest that mesolimbic brain regions support the computation of EV in an ascending and distributed manner: whereas subcortical regions represent an affective component, cortical regions also represent a probabilistic component, and, furthermore, may integrate the two.

    View details for DOI 10.1523/JNEUROSCI.0642-05.2005

    View details for Web of Science ID 000229038300014

    View details for PubMedID 15888656

  • Remembrance of rewards past NEURON Knutson, B., Adcock, R. A. 2005; 45 (3): 331-332

    Abstract

    Using event-related fMRI, Wittmann and colleagues report in this issue of Neuron that reward value enhances cue memory and that this process is associated with midbrain modulation of hippocampal consolidation. We propose that their findings introduce a novel mechanism by which positive arousal induced by reward anticipation may promote memory.

    View details for DOI 10.1016/j.neuron.2005.01.020

    View details for Web of Science ID 000226787700004

    View details for PubMedID 15694318

  • Sweet revenge? SCIENCE Knutson, B. 2004; 305 (5688): 1246-1247

    View details for Web of Science ID 000223624600027

    View details for PubMedID 15333827

  • Amphetamine modulates human incentive processing NEURON Knutson, B., Bjork, J. M., Fong, G. W., Hommer, D., Mattay, V. S., Weinberger, D. R. 2004; 43 (2): 261-269

    Abstract

    Research suggests that psychostimulants can physiologically alter dopamine kinetics in the ventral striatum (VS) and psychologically enhance mood and attention. Using event-related functional magnetic resonance imaging (fMRI), we conducted a within-subject, double-blind, placebo (PLAC)-controlled study of the effects of oral dextroamphetamine (AMPH, 0.25 mg/kg) treatment on brain activity and affect during incentive processing. In two counterbalanced scanning sessions 60-180 min after ingesting AMPH or PLAC, 8 healthy volunteers played a game involving anticipation and receipt of monetary gains and losses. Group and volume of interest analyses suggested that by enhancing tonic over phasic activation, AMPH treatment "equalized" levels of VS activity and positive arousal during anticipation of both gain and loss. These findings suggest that therapeutic effects of amphetamine on incentive processing may involve reducing the difference between anticipation of gains and losses.

    View details for Web of Science ID 000222905400014

    View details for PubMedID 15260961

  • Voxel-based homogeneity probability maps of grapy matter in groups: assessing the reliability of functional effects NEUROIMAGE Momenan, R., Rawlings, R., Fong, G., Knutson, B., Hommer, D. 2004; 21 (3): 965-972

    Abstract

    A subject of increasing importance in magnetic resonance imaging (MRI) is the analysis of intersubject structural differences, particularly when comparing groups of subjects with different conditions or diagnoses. On the other hand, determining structural homogeneity across subjects using voxel-based morphological (VBM) methods has become even more important to investigators who test for group brain activation using functional magnetic resonance images (fMRI) or positron emission tomography (PET). In the absence of methods that evaluate structural differences, one does not know how much reliability to assign to the functional differences. Here, we describe a voxel-based method for quantitatively assessing the homogeneity of tissues from structural magnetic resonance images of groups. Specifically, this method determines the homogeneity of gray matter for a group of subjects. Homogeneity probability maps (HPMs) of a given tissue type (e.g., gray matter) are generated by using a confidence interval based on binomial distribution. These maps indicate for each voxel the probability that the tissue type is gray for the population being studied. Therefore, HPMs can accompany functional analyses to indicate the confidence one can assign to functional difference at any given voxel. In this paper, examples of HPMs generated for a group of control subjects are shown and discussed. The application of this method to functional analysis is demonstrated.

    View details for DOI 10.1016/j.neuroimage.2003.10.038

    View details for Web of Science ID 000220148900017

    View details for PubMedID 15006663

  • Incentive-elicited brain activation in adolescents: Similarities and differences from young adults JOURNAL OF NEUROSCIENCE Bjork, J. M., Knutson, B., Fong, G. W., Caggiano, D. M., Bennett, S. M., Hommer, D. W. 2004; 24 (8): 1793-1802

    Abstract

    Brain motivational circuitry in human adolescence is poorly characterized. One theory holds that risky behavior in adolescence results in part from a relatively overactive ventral striatal (VS) motivational circuit that readily energizes approach toward salient appetitive cues. However, other evidence fosters a theory that this circuit is developmentally underactive, in which adolescents approach more robust incentives (such as risk taking or drug experimentation) to recruit this circuitry. To help resolve this, we compared brain activation in 12 adolescents (12-17 years of age) and 12 young adults (22-28 years of age) while they anticipated the opportunity to respond to obtain monetary gains as well as to avoid monetary losses. In both age groups, anticipation of potential gain activated portions of the VS, right insula, dorsal thalamus, and dorsal midbrain, where the magnitude of VS activation was sensitive to gain amount. Notification of gain outcomes (in contrast with missed gains) activated the mesial frontal cortex (mFC). Across all subjects, signal increase in the right nucleus accumbens during anticipation of responding for large gains independently correlated with both age and self-rated excitement about the high gain cue. In direct comparison, adolescents evidenced less recruitment of the right VS and right-extended amygdala while anticipating responding for gains (in contrast with anticipation of nongains) compared with young adults. However, brain activation after gain outcomes did not appreciably differ between age groups. These results suggest that adolescents selectively show reduced recruitment of motivational but not consummatory components of reward-directed behavior.

    View details for DOI 10.1523/JNEUROSCI.4862-03.2004

    View details for Web of Science ID 000189210300001

    View details for PubMedID 14985419

  • A region of mesial prefrontal cortex tracks monetarily rewarding outcomes: characterization with rapid event-related fMRI NEUROIMAGE Knutson, B., Fong, G. W., Bennett, S. M., Adams, C. M., Homme, D. 2003; 18 (2): 263-272

    Abstract

    The function of the mesial prefrontal cortex (MPFC: including Brodman areas 10/12/32) remains an enigma. Current theories suggest a role in representing internal information, including emotional introspection, autonomic control, and a "default state" of semantic processing. Recent evidence also suggests that parts of this region may also play a role in processing reward outcomes. In this study, we investigated the possibility that a region of the MPFC would be preferentially recruited by monetary reward outcomes using a parametric monetary incentive delay (MID) task. Twelve healthy volunteers participated in functional magnetic resonance scans while playing the MID task. Group analyses indicated that while the ventral striatum was recruited by anticipation of monetary reward, a region of the MPFC instead responded to rewarding monetary outcomes. Specifically, volume-of-interest analyses indicated that when volunteers received $5.00 after anticipating a $5.00 win, MPFC activity increased, whereas when volunteers did not receive $5.00 after anticipating a $5.00 win, MPFC activity decreased, relative to outcomes with no incentive value. These findings suggest that in the context of processing monetary rewards, a region of the MPFC preferentially tracks rewarding outcomes.

    View details for DOI 10.1016/S1053-8119(02)00057-5

    View details for Web of Science ID 000181182500007

    View details for PubMedID 12595181

  • Amygdalar recruitment during anticipation of monetary rewards - An event-related fMRI study AMYGDALA IN BRAIN FUNCTION: BASIC AND CLINICAL APPROACHES Hommer, D. W., Knutson, B., Fong, G. W., Bennett, S., Adams, C. M., Varner, J. L. 2003; 985: 476-478

    View details for Web of Science ID 000182918800037

    View details for PubMedID 12724180

  • Ultrasonic Vocalizations as indices of affective states in rats PSYCHOLOGICAL BULLETIN Knutson, B., Burgdorf, J., Panksepp, J. 2002; 128 (6): 961-977

    Abstract

    Adult rats spontaneously vocalize in ultrasonic frequencies. Although these ultrasonic vocalizations (USVs) have been described as by-products of locomotor activity or social signals, accumulating evidence suggests that they may also index anticipatory affective states. Converging ethological, pharmacological, and brain stimulation research indicates that whereas long low-frequency (> 0.3-s, approximately 22-kHz) USVs occur during anticipation of punishment or avoidance behavior, short, high-frequency (< 0.3-s, approximately 50-kHz) USVs typically occur during anticipation of reward or approach behavior. Thus, long 22-kHz USVs may index a state of negative activation, whereas short, 50-kHz USVs may instead index a state of positive activation. This hypothesis has theoretical implications for understanding the brain circuitry underlying mammalian affective states and clinical applicability for modeling hedonic properties of different psychotropic compounds.

    View details for DOI 10.1037//0033-2909.128.6.961

    View details for Web of Science ID 000178726100005

    View details for PubMedID 12405139

  • The role of brain emotional systems in addictions: a neuro-evolutionary perspective and new 'self-report' animal model ADDICTION Panksepp, J., Knutson, B., Burgdorf, J. 2002; 97 (4): 459-469

    Abstract

    The evolutionary significance of neurochemical events in the brain has received minimal attention in the field of addiction research. Likewise, the general failure of neuroscientists to postulate how basic brain circuits might mediate emotional urges has retarded the development of scientific perspectives that could inform new inquiries into the underlying dynamics and treatment of addictions. In this paper, we revisit the argument that prototypically abused substances activate or alter specific emotional brain systems that were evolutionarily designed to signal potential increments or decrements in fitness. We then discuss two distinct emotional systems (reward seeking and separation distress) which may track different types of potential changes in fitness. Based on this evolutionarily inspired approach, we illustrate how a mammalian model of emotion (i.e. rodent ultrasonic vocalizations) may enable scientists to predict drug-related phenomena such as abuse potential, anatomical location of mediating neural substrates, and the psychological impact of withdrawal. We conclude by discussing some therapeutic and social implications of examining drug addiction processes with multiple emotional brain systems in mind.

    View details for Web of Science ID 000174850900009

    View details for PubMedID 11964061

  • Dissociation of reward anticipation and outcome with event-related fMRI NEUROREPORT Knutson, B., Fong, G. W., Adams, C. M., Varner, J. L., Hommer, D. 2001; 12 (17): 3683-3687

    Abstract

    Reward processing involves both appetitive and consummatory phases. We sought to examine whether reward anticipation vs outcomes would recruit different regions of ventral forebrain circuitry using event-related fMRI. Nine healthy volunteers participated in a monetary incentive delays task in which they either responded to a cued target for monetary reward, responded to a cued target for no reward, or did not respond to a cued target during scanning. Multiple regression analyses indicated that while anticipation of reward vs non-reward activated foci in the ventral striatum, reward vs non-reward outcomes activated foci in the ventromedial frontal cortex. These findings suggest that reward anticipation and outcomes may differentially recruit distinct regions that lie along the trajectory of ascending dopamine projections.

    View details for Web of Science ID 000172397000012

    View details for PubMedID 11726774

  • Negative association of neuroticism with brain volume ratio in healthy humans BIOLOGICAL PSYCHIATRY Knutson, B., Momenan, R., RAWLINGS, R. R., Fong, G. W., Hommer, D. 2001; 50 (9): 685-690

    Abstract

    Brain volume decreases with normal aging. We sought to determine whether, in addition to age, individual differences in stress reactivity (i.e., neuroticism) would also predict reductions in brain volume.Brain volume ratios were calculated for a sample of 86 healthy volunteers, based on segmented brain volumes taken from T(1)-weighted magnetic resonance imaging and corrected for intracranial volume. Standardized self-reported measures of dispositional neuroticism were concurrently obtained by administering the Revised NEO Personality Inventory.After statistically controlling for age and sex, neuroticism showed a significant negative association with the ratio of brain to the remainder of the intracranial volume, but was not related to intracranial volume itself. In particular, subfactors of neuroticism related to the chronic experience of arousing negative emotions were associated with reduced brain ratio.These results suggest that individual differences in stress reactivity contribute to reductions in brain volume observed during adulthood.

    View details for Web of Science ID 000172035100005

    View details for PubMedID 11704075

  • Anticipation of increasing monetary reward selectively recruits nucleus accumbens JOURNAL OF NEUROSCIENCE Knutson, B., Adams, C. M., Fong, G. W., Hommer, D. 2001; 21 (16)

    Abstract

    Comparative studies have implicated the nucleus accumbens (NAcc) in the anticipation of incentives, but the relative responsiveness of this neural substrate during anticipation of rewards versus punishments remains unclear. Using event-related functional magnetic resonance imaging, we investigated whether the anticipation of increasing monetary rewards and punishments would increase NAcc blood oxygen level-dependent contrast (hereafter, "activation") in eight healthy volunteers. Whereas anticipation of increasing rewards elicited both increasing self-reported happiness and NAcc activation, anticipation of increasing punishment elicited neither. However, anticipation of both rewards and punishments activated a different striatal region (the medial caudate). At the highest reward level ($5.00), NAcc activation was correlated with individual differences in self-reported happiness elicited by the reward cues. These findings suggest that whereas other striatal areas may code for expected incentive magnitude, a region in the NAcc codes for expected positive incentive value.

    View details for Web of Science ID 000170318200001

    View details for PubMedID 11459880

  • Nucleus accumbens amphetamine microinjections unconditionally elicit 50-kHz ultrasonic vocalizations in rats BEHAVIORAL NEUROSCIENCE Burgdorf, J., Knutson, B., Panksepp, J., Ikemoto, S. 2001; 115 (4): 940-944

    Abstract

    The authors have hypothesized that, in adult rats, 50-kHz ultrasonic vocalizations (USVs) index a state characterized by high arousal and expectations of reward. This study was conducted to investigate whether dopamine agonism of the nucleus accumbens (NAcc) could evoke such an appetitive state, by examining the effects of NAcc amphetamine (AMPH) microinjections on USVs. Intra-NAcc AMPH injections (0.3, 1.0, 3.0, 10.0 microg unilaterally) produced robust, dose-dependent increases in 50-kHz USVs, which could not be accounted for by concomitant increases in locomotor activity (LA). However, AMPH injections into dorsal control caudate putamen sites produced a modest, dose-dependent increase in LA without significant increases in 50-kHz USVs. These findings indicate that NAcc AMPH microinjections selectively evoke 50-kHz USVs in rats, supporting the notion that dopamine elevations in the NAcc may unconditionally elicit a state of reward anticipation.

    View details for Web of Science ID 000170911600020

    View details for PubMedID 11508733

  • Evaluation of rat ultrasonic vocalizations as predictors of the conditioned aversive effects of drugs PSYCHOPHARMACOLOGY Burgdorf, J., Knutson, B., Panksepp, J., Shippenberg, T. S. 2001; 155 (1): 35-42

    Abstract

    Since cues that predict aversive outcomes can elicit both avoidance and 20 kHz ultrasonic vocalizations (USVs) in adult rats, 20 kHz USVs may also index the conditioned aversive effects of drugs.We evaluated whether exposure to compartments associated with drugs with aversive effects would selectively increase 20 but not 50 kHz USVs in rats.Rats were injected with naloxone (NAL) or lithium chloride (LiCl) and placed in one compartment or with saline (VEH) and placed in another compartment for three 50-min conditioning sessions. 20 kHz USVs, 50 kHz USVs, and time spent in each chamber were recorded during subsequent 15-min testing sessions during which rats had access to both compartments (expt 1) or were confined to the drug- or VEH-paired compartment (expt 2).In expt 1, animals conditioned either with NAL (0.3 and 3.0 mg/kg) or LiCl (10 and 30 mg/kg) emitted increased 20 kHz USVs in the drug-paired compartment, relative to VEH-conditioned controls. Conditioning with high doses of both drugs also increased conditioned place aversion and decreased emission of 50 kHz USVs. In expt 2, restriction of animals to the compartment paired with high doses of NAL and LiCl also increased emission of 20 kHz USVs and decreased 50 kHz USVs, relative to VEH-conditioned controls.In rats, cues associated with drugs with aversive effects increase 20 kHz USVs and decrease 50 kHz USVs, suggesting that USVs may provide a useful model for predicting the conditioned aversive effects of drugs.

    View details for Web of Science ID 000168522200005

    View details for PubMedID 11374334

  • FMRI visualization of brain activity during a monetary incentive delay task NEUROIMAGE Knutson, B., Westdorp, A., Kaiser, E., Hommer, D. 2000; 12 (1): 20-27

    Abstract

    Comparative studies have implicated striatal and mesial forebrain circuitry in the generation of autonomic, endocrine, and behavioral responses for incentives. Using blood oxygen level-dependent functional magnetic resonance imaging, we sought to visualize functional activation of these regions in 12 normal volunteers as they anticipated and responded for monetary incentives. Both individual and group analyses of time-series data revealed significant activation of striatal and mesial forebrain structures (including insula, caudate, putamen, and mesial prefrontal cortex) during trials involving both monetary rewards and punishments. In addition to these areas, during trials involving punishment, group analysis revealed activation foci in the anterior cingulate and thalamus. These results corroborate comparative studies which implicate striatal and mesial forebrain circuitry in the elaboration of incentive-driven behavior. This report also introduces a new paradigm for probing the functional integrity of this circuitry in humans.

    View details for Web of Science ID 000088317700003

    View details for PubMedID 10875899

  • Anticipation of rewarding electrical brain stimulation evokes ultrasonic vocalization in rats BEHAVIORAL NEUROSCIENCE Burgdorf, J., Knutson, B., Panksepp, J. 2000; 114 (2): 320-327

    Abstract

    Adult rats emit increased rates of 50-kHz ultrasonic vocalizations (USVs) before receiving social and pharmacological rewards. This study sought to determine whether anticipation of rewarding electrical stimulation of the brain (ESB) would also elicit these vocalizations. In Experiments 1 and 2, rats showed increased 50-kHz USVs before receiving experimenter-delivered ventral tegmental area (VTA) and lateral hypothalamic (LH) ESB on a fixed time 20-s schedule. In Experiments 3 and 4, rats increased their rate of 50-kHz USVs in response to cues that predicted the opportunity to self-stimulate the VTA or LH. Interestingly, unexpected termination of either type of ESB evoked 20-kHz, rather than 50-kHz, USVs. In Experiment 5, a cue that predicted daily 1-hr feeding sessions increased 50-kHz USVs, whereas a cue that predicted footshock decreased 50-kHz USVs. These effects could not be explained simply by changes in locomotor activity or general arousal. Together, these findings support the hypothesis that short 50-kHz USVs may selectively index a state of reward anticipation in rats.

    View details for DOI 10.1037//0735-7044.114.2.320

    View details for Web of Science ID 000087492200010

    View details for PubMedID 10832793

  • High-frequency ultrasonic vocalizations index conditioned pharmacological reward in rats PHYSIOLOGY & BEHAVIOR Knutson, B., Burgdorf, J., Panksepp, J. 1999; 66 (4): 639-643

    Abstract

    We have proposed that short (<0.5 s), high-frequency (approximately 50 kHz) ultrasonic vocalizations ("50-kHz USVs") index a positive affective state in adult rats, because they occur prior to rewarding social interactions (i.e., rough-and-tumble play, sex). To evaluate this hypothesis in the case of nonsocial stimuli, we examined whether rats would make increased 50-kHz USVs in places associated with the administration of rewarding pharmacological compounds [i.e., amphetamine (AMPH) and morphine (MORPH)]. In Experiment 1, rats made a greater percentage of 50-kHz USVs on the AMPH-paired side of a two-compartment chamber than on the vehicle-paired side, even after statistical correction for place preference. In Experiment 2, rats made a higher percentage of 50-kHz USVs on the MORPH-paired side than on the vehicle-paired side, despite nonsignificant place preference. These findings support the hypothesis that 50-kHz USVs mark a positive affective state in rats and introduce a novel and rapid marker of pharmacological reward.

    View details for Web of Science ID 000080685000013

    View details for PubMedID 10386908

  • Anticipation of play elicits high-frequency ultrasonic vocalizations in young rats JOURNAL OF COMPARATIVE PSYCHOLOGY Knutson, B., Burgdorf, J., Panksepp, J. 1998; 112 (1): 65-73

    Abstract

    The authors provide initial documentation that juvenile rats emit short, high-frequency ultrasonic vocalizations (high USVs, approximately 55 kHz) during rough-and-tumble play. In an observational study, they further observe that these vocalizations both correlate with and predict appetitive components of the play behavioral repertoire. Additional experiments characterized eliciting conditions for high USVs. Without prior play exposure, rats separated by a screen vocalized less than playing rats, but after only 1 play session, separated rats vocalized more than playing rats. This findings suggested that high USVs were linked to a motivational state rather than specific play behaviors or general activity. Furthermore, individual rats vocalized more in a chamber associated with play than in a habituated control chamber. Finally, congruent and incongruent motivational manipulations modulated vocalization expression. Although play deprivation enhanced high USVs, an arousing but aversive stimulus (bright light) reduced them. Taken together, these findings suggest that high USVs may index an appetitive motivation to play in juvenile rats.

    View details for Web of Science ID 000072487600007

    View details for PubMedID 9528115

  • Effects of serotonin depletion on the play of juvenile rats INTEGRATIVE NEUROBIOLOGY OF AFFILIATION Knutson, B., Panksepp, J. 1997; 807: 475-477

    View details for Web of Science ID A1997BJ17S00033

    View details for PubMedID 9071373

  • Effects of fluoxetine on play dominance in juvenile rats AGGRESSIVE BEHAVIOR Knutson, B., Panksepp, J., Pruitt, D. 1996; 22 (4): 297-307
  • ON THE BRAIN AND PERSONALITY SUBSTRATES OF PSYCHOPATHY BEHAVIORAL AND BRAIN SCIENCES Panksepp, J., Knutson, B., Bird, L. 1995; 18 (3): 568-570

Conference Proceedings


  • SPATIAL SMOOTHING AND THE FUNCTIONAL LOCALIZATION OF NUCLEUS ACCUMBENS ACTIVITY Sacchet, M., Knutson, B. MIT PRESS. 2013: 231-232
  • REINFORCEMENT LEARNING AND AGE-RELATED CHANGES IN RELATIVE CODING IN MESOLIMBIC BRAIN REGIONS Samanez-Larkin, G. R., Worthy, D. A., McClure, S. M., Knutson, B. OXFORD UNIV PRESS INC. 2010: 10-10
  • Facial EMG discriminates gain and loss anticipation and outcome in a monetary incentive delay task NIELSEN, L., Knutson, B., Kaufman, M., Weinstein, L., Carstensen, L. L. WILEY-BLACKWELL. 2004: S80-S80

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