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  • 1
    Online Resource
    Online Resource
    De Novo Emergence of Odor Category Representations in the Human Brain
    Society for Neuroscience ; 2016
    In:  The Journal of Neuroscience Vol. 36, No. 2 ( 2016-01-13), p. 468-478
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 36, No. 2 ( 2016-01-13), p. 468-478
    Abstract: Categorization allows organisms to efficiently extract relevant information from a diverse environment. Because of the multidimensional nature of odor space, this ability is particularly important for the olfactory system. However, categorization relies on experience, and the processes by which the human brain forms categorical representations about new odor percepts are currently unclear. Here we used olfactory psychophysics and multivariate fMRI techniques, in the context of a paired-associates learning task, to examine the emergence of novel odor category representations in the human brain. We found that learning between novel odors and visual category information induces a perceptual reorganization of those odors, in parallel with the emergence of odor category-specific ensemble patterns in perirhinal, orbitofrontal, piriform, and insular cortices. Critically, the learning-induced pattern effects in orbitofrontal and perirhinal cortex predicted the magnitude of categorical learning and perceptual plasticity. The formation of de novo category-specific representations in olfactory and limbic brain regions suggests that such ensemble patterns subserve the development of perceptual classes of information, and imply that these patterns are instrumental to the brain's capacity for odor categorization. SIGNIFICANCE STATEMENT How the human brain assigns novel odors to perceptual classes and categories is poorly understood. We combined an olfactory-visual paired-associates task with multivariate pattern-based fMRI approaches to investigate the de novo formation of odor category representations within the human brain. The identification of emergent odor category codes within the perirhinal, piriform, orbitofrontal, and insular cortices suggests that these regions can integrate multimodal sensory input to shape category-specific olfactory representations for novel odors, and may ultimately play an important role in assembling each individual's semantic knowledge base of the olfactory world.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.3248-15.2016
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2016
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Neurobiology of Value Integration: When Value Impacts Valuation
    Society for Neuroscience ; 2011
    In:  Journal of Neuroscience Vol. 31, No. 25 ( 2011-06-22), p. 9307-9314
    Details
    In: Journal of Neuroscience, Society for Neuroscience, Vol. 31, No. 25 ( 2011-06-22), p. 9307-9314
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.4973-10.2011
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2011
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 3
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    Online Resource
    How Glitter Relates to Gold: Similarity-Dependent Reward Prediction Errors in the Human Striatum
    Society for Neuroscience ; 2012
    In:  The Journal of Neuroscience Vol. 32, No. 46 ( 2012-11-14), p. 16521-16529
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 32, No. 46 ( 2012-11-14), p. 16521-16529
    Abstract: Optimal choices benefit from previous learning. However, it is not clear how previously learned stimuli influence behavior to novel but similar stimuli. One possibility is to generalize based on the similarity between learned and current stimuli. Here, we use neuroscientific methods and a novel computational model to inform the question of how stimulus generalization is implemented in the human brain. Behavioral responses during an intradimensional discrimination task showed similarity-dependent generalization. Moreover, a peak shift occurred, i.e., the peak of the behavioral generalization gradient was displaced from the rewarded conditioned stimulus in the direction away from the unrewarded conditioned stimulus. To account for the behavioral responses, we designed a similarity-based reinforcement learning model wherein prediction errors generalize across similar stimuli and update their value. We show that this model predicts a similarity-dependent neural generalization gradient in the striatum as well as changes in responding during extinction. Moreover, across subjects, the width of generalization was negatively correlated with functional connectivity between the striatum and the hippocampus. This result suggests that hippocampus–striatal connections contribute to stimulus-specific value updating by controlling the width of generalization. In summary, our results shed light onto the neurobiology of a fundamental, similarity-dependent learning principle that allows learning the value of stimuli that have never been encountered.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.2383-12.2012
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2012
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 4
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    Online Resource
    Targeted Stimulation of an Orbitofrontal Network Disrupts Decisions Based on Inferred, Not Experienced Outcomes
    Society for Neuroscience ; 2020
    In:  The Journal of Neuroscience Vol. 40, No. 45 ( 2020-11-04), p. 8726-8733
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    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 40, No. 45 ( 2020-11-04), p. 8726-8733
    Abstract: When direct experience is unavailable, animals and humans can imagine or infer the future to guide decisions. Behavior based on direct experience versus inference may recruit partially distinct brain circuits. In rodents, the orbitofrontal cortex (OFC) contains neural signatures of inferred outcomes, and OFC is necessary for behavior that requires inference but not for responding driven by direct experience. In humans, OFC activity is also correlated with inferred outcomes, but it is unclear whether OFC activity is required for inference-based behavior. To test this, we used noninvasive network-based continuous theta burst stimulation (cTBS) in human subjects (male and female) to target lateral OFC networks in the context of a sensory preconditioning task that was designed to isolate inference-based behavior from responding that can be based on direct experience alone. We show that, relative to sham, cTBS targeting this network impairs reward-related behavior in conditions in which outcome expectations have to be mentally inferred. In contrast, OFC-targeted stimulation does not impair behavior that can be based on previously experienced stimulus–outcome associations. These findings suggest that activity in the targeted OFC network supports decision-making when outcomes have to be mentally simulated, providing converging cross-species evidence for a critical role of OFC in model-based but not model-free control of behavior. SIGNIFICANCE STATEMENT It is widely accepted that the orbitofrontal cortex (OFC) is important for decision-making. However, it is less clear how exactly this region contributes to behavior. Here we test the hypothesis that the human OFC is only required for decision-making when future outcomes have to be mentally simulated, but not when direct experience with stimulus–outcome associations is available. We show that targeting OFC network activity in humans using network-based continuous theta burst stimulation selectively impairs behavior that requires inference but does not affect responding that can be based solely on direct experience. These results are in line with previous findings in animals and suggest a critical role for human OFC in model-based but not model-free behavior.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.1680-20.2020
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2020
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 5
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    Online Resource
    Decoding the Formation of Reward Predictions across Learning
    Society for Neuroscience ; 2011
    In:  The Journal of Neuroscience Vol. 31, No. 41 ( 2011-10-12), p. 14624-14630
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 31, No. 41 ( 2011-10-12), p. 14624-14630
    Abstract: The predicted reward of different behavioral options plays an important role in guiding decisions. Previous research has identified reward predictions in prefrontal and striatal brain regions. Moreover, it has been shown that the neural representation of a predicted reward is similar to the neural representation of the actual reward outcome. However, it has remained unknown how these representations emerge over the course of learning and how they relate to decision making. Here, we sought to investigate learning of predicted reward representations using functional magnetic resonance imaging and multivariate pattern classification. Using a pavlovian conditioning procedure, human subjects learned multiple novel cue–outcome associations in each scanning run. We demonstrate that across learning activity patterns in the orbitofrontal cortex, the dorsolateral prefrontal cortex (DLPFC), and the dorsal striatum, coding the value of predicted rewards become similar to the patterns coding the value of actual reward outcomes. Furthermore, we provide evidence that predicted reward representations in the striatum precede those in prefrontal regions and that representations in the DLPFC are linked to subsequent value-based choices. Our results show that different brain regions represent outcome predictions by eliciting the neural representation of the actual outcome. Furthermore, they suggest that reward predictions in the DLPFC are directly related to value-based choices.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.3412-11.2011
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2011
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 6
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    Online Resource
    Orbitofrontal Signaling of Future Reward is Associated with Hyperactivity in Attention-Deficit/Hyperactivity Disorder
    Society for Neuroscience ; 2018
    In:  The Journal of Neuroscience Vol. 38, No. 30 ( 2018-07-25), p. 6779-6786
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 38, No. 30 ( 2018-07-25), p. 6779-6786
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.0411-18.2018
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2018
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 7
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    Online Resource
    Mapping the Microstructure and Striae of the Human Olfactory Tract with Diffusion MRI
    Society for Neuroscience ; 2022
    In:  The Journal of Neuroscience Vol. 42, No. 1 ( 2022-01-05), p. 58-68
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 42, No. 1 ( 2022-01-05), p. 58-68
    Abstract: The human sense of smell plays an important role in appetite and food intake, detecting environmental threats, social interactions, and memory processing. However, little is known about the neural circuity supporting its function. The olfactory tracts project from the olfactory bulb along the base of the frontal cortex, branching into several striae to meet diverse cortical regions. Historically, using diffusion magnetic resonance imaging (dMRI) to reconstruct the human olfactory tracts has been prevented by susceptibility and motion artifacts. Here, we used a dMRI method with readout segmentation of long variable echo-trains (RESOLVE) to minimize image distortions and characterize the human olfactory tracts in vivo . We collected high-resolution dMRI data from 25 healthy human participants (12 male and 13 female) and performed probabilistic tractography using constrained spherical deconvolution (CSD). At the individual subject level, we identified the lateral, medial, and intermediate striae with their respective cortical connections to the piriform cortex and amygdala (AMY), olfactory tubercle (OT), and anterior olfactory nucleus (AON). We combined individual results across subjects to create a normalized, probabilistic atlas of the olfactory tracts. We then investigated the relationship between olfactory perceptual scores and measures of white matter integrity, including mean diffusivity (MD). Importantly, we found that olfactory tract MD negatively correlated with odor discrimination performance. In summary, our results provide a detailed characterization of the connectivity of the human olfactory tracts and demonstrate an association between their structural integrity and olfactory perceptual function. SIGNIFICANCE STATEMENT This study provides the first detailed in vivo description of the cortical connectivity of the three olfactory tract striae in the human brain, using diffusion magnetic resonance imaging (dMRI). Additionally, we show that tract microstructure correlates with performance on an odor discrimination task, suggesting a link between the structural integrity of the olfactory tracts and odor perception. Lastly, we generated a normalized probabilistic atlas of the olfactory tracts that may be used in future research to study its integrity in health and disease.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.1552-21.2021
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2022
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 8
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    Online Resource
    Prefrontal Cortex Fails to Learn from Reward Prediction Errors in Alcohol Dependence
    Society for Neuroscience ; 2010
    In:  The Journal of Neuroscience Vol. 30, No. 22 ( 2010-06-02), p. 7749-7753
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 30, No. 22 ( 2010-06-02), p. 7749-7753
    Abstract: Patients suffering from addiction persist in consuming substances of abuse, despite negative consequences or absence of positive consequences. One potential explanation is that these patients are impaired at flexibly adapting their behavior to changes in reward contingencies. A key aspect of adaptive decision-making involves updating the value of behavioral options. This is thought to be mediated via a teaching signal expressed as a reward prediction error (PE) in the striatum. However, to exert control over adaptive behavior, value signals need to be broadcast to higher executive regions, such as prefrontal cortex. Here we used functional MRI and a reinforcement learning task to investigate the neural mechanisms underlying maladaptive behavior in human male alcohol-dependent patients. We show that in alcohol-dependent patients the expression of striatal PEs is intact. However, abnormal functional connectivity between striatum and dorsolateral prefrontal cortex (dlPFC) predicted impairments in learning and the magnitude of alcohol craving. These results are in line with reports of dlPFC structural abnormalities in substance dependence and highlight the importance of frontostriatal connectivity in addiction, and its pivotal role in adaptive updating of action values and behavioral regulation. Furthermore, they extend the scope of neurobiological deficits underlying addiction beyond the focus on the striatum.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.5587-09.2010
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2010
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 9
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    Online Resource
    Neural Integration of Risk and Effort Costs by the Frontal Pole: Only upon Request
    Society for Neuroscience ; 2013
    In:  The Journal of Neuroscience Vol. 33, No. 4 ( 2013-01-23), p. 1706-1713
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 33, No. 4 ( 2013-01-23), p. 1706-1713
    Abstract: Rewards in real life are rarely received without incurring costs and successful reward harvesting often involves weighing and minimizing different types of costs. In the natural environment, such costs often include the physical effort required to obtain rewards and potential risks attached to them. Costs may also include potential risks. In this study, we applied fMRI to explore the neural coding of physical effort costs as opposed to costs associated with risky rewards. Using an incentive-compatible valuation mechanism, we separately measured the subjective costs associated with effortful and risky options. As expected, subjective costs of options increased with both increasing effort and increasing risk. Despite the similar nature of behavioral discounting of effort and risk, distinct regions of the brain coded these two cost types separately, with anterior insula primarily processing risk costs and midcingulate and supplementary motor area (SMA) processing effort costs. To investigate integration of the two cost types, we also presented participants with options that combined effortful and risky elements. We found that the frontal pole integrates effort and risk costs through functional coupling with the SMA and insula. The degree to which the latter two regions influenced frontal pole activity correlated with participant-specific behavioral sensitivity to effort and risk costs. These data support the notion that, although physical effort costs may appear to be behaviorally similar to other types of costs, such as risk, they are treated separately at the neural level and are integrated only if there is a need to do so.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.3662-12.2013
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2013
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 10
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    Online Resource
    Identity-Specific Reward Representations in Orbitofrontal Cortex Are Modulated by Selective Devaluation
    Society for Neuroscience ; 2017
    In:  The Journal of Neuroscience Vol. 37, No. 10 ( 2017-03-08), p. 2627-2638
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 37, No. 10 ( 2017-03-08), p. 2627-2638
    Abstract: Goal-directed behavior is sensitive to the current value of expected outcomes. This requires independent representations of specific rewards, which have been linked to orbitofrontal cortex (OFC) function. However, the mechanisms by which the human brain updates specific goals on the fly, and translates those updates into choices, have remained unknown. Here we implemented selective devaluation of appetizing food odors in combination with pattern-based neuroimaging and a decision-making task. We found that in a hungry state, participants chose to smell high-intensity versions of two value-matched food odor rewards. After eating a meal corresponding to one of the two odors, participants switched choices toward the low intensity of the sated odor but continued to choose the high intensity of the nonsated odor. This sensory-specific behavioral effect was mirrored by pattern-based changes in fMRI signal in lateral posterior OFC, where specific reward identity representations were altered after the meal for the sated food odor but retained for the nonsated counterpart. In addition, changes in functional connectivity between the OFC and general value coding in ventromedial prefrontal cortex (vmPFC) predicted individual differences in satiety-related choice behavior. These findings demonstrate how flexible representations of specific rewards in the OFC are updated by devaluation, and how functional connections to vmPFC reflect the current value of outcomes and guide goal-directed behavior. SIGNIFICANCE STATEMENT The orbitofrontal cortex (OFC) is critical for goal-directed behavior. A recent proposal is that OFC fulfills this function by representing a variety of state and task variables (“cognitive maps”), including a conjunction of expected reward identity and value. Here we tested how identity-specific representations of food odor reward are updated by satiety. We found that fMRI pattern-based signatures of reward identity in lateral posterior OFC were modulated after selective devaluation, and that connectivity between this region and general value coding ventromedial prefrontal cortex (vmPFC) predicted choice behavior. These results provide evidence for a mechanism by which devaluation modulates a cognitive map of expected reward in OFC and thereby alters general value signals in vmPFC to guide goal-directed behavior.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.3473-16.2017
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2017
    detail.hit.zdb_id: 1475274-8
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