Thorsten Kahnt

Thorsten Kahnt
NIDA Intramural Research Program · Cellular and Neurocomputational Systems Branch

PhD

About

82
Publications
10,565
Reads
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4,606
Citations
Additional affiliations
June 2014 - present
Northwestern University Feinberg School of Medicine
Position
  • Professor (Assistant)
May 2011 - June 2014
University of Zurich
Position
  • Laboratory for Social and Neural Systems Research
October 2007 - April 2011
Charité Universitätsmedizin Berlin
Position
  • Bernstein Center for Computational Neuroscience Berlin

Publications

Publications (82)
Article
Full-text available
Nervous systems must encode information about the identity of expected outcomes to make adaptive decisions. However, the neural mechanisms underlying identity-specific value signaling remain poorly understood. By manipulating the value and identity of appetizing food odors in a pattern-based imaging paradigm of human classical conditioning, we were...
Article
Full-text available
The prefrontal cortex houses representations critical for ongoing and future behavior expressed in the form of patterns of neural activity. Dopamine has long been suggested to play a key role in the integrity of such representations, with D2-receptor activation rendering them flexible but weak. However, it is currently unknown whether and how D2-re...
Article
Full-text available
A large body of evidence has implicated the posterior parietal and orbitofrontal cortex in the processing of value. However, value correlates perfectly with salience when appetitive stimuli are investigated in isolation. Accordingly, considerable uncertainty has remained about the precise nature of the previously identified signals. In particular,...
Article
Full-text available
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 stim...
Article
The dominant view that perceptual learning is accompanied by changes in early sensory representations has recently been challenged. Here we tested the idea that perceptual learning can be accounted for by reinforcement learning involving changes in higher decision-making areas. We trained subjects on an orientation discrimination task involving fee...
Article
Full-text available
Theoretical accounts distinguish between motivational ('wanting') and hedonic ('liking') dimensions of rewards. Previous animal and human research linked wanting and liking to anatomically and neurochemically distinct brain mechanisms, but it remains unknown how the different brain regions and neurotransmitter systems interact in processing distinc...
Article
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 stria...
Article
In novel situations, where direct experience is lacking or outdated, humans must rely on mental simulations to predict future outcomes. This review discusses recent work on the neural circuits that support such inference-based behavior. We focus on two specific examples: (1) using knowledge about the associative structure of the world to infer outc...
Article
Growing evidence suggests that internal factors influence how we perceive the world. However, it remains unclear whether and how motivational states, such as hunger and satiety, regulate perceptual decision-making in the olfactory domain. Here, we developed a novel behavioral task involving mixtures of food and nonfood odors (i.e., cinnamon bun and...
Article
Learning associations between sensory stimuli and outcomes, and generalizing these associations to novel stimuli, are a fundamental feature of adaptive behavior. Given a noisy olfactory world, stimulus generalization holds unique relevance for the olfactory system. Recent studies suggest that aversive outcomes induce wider generalization curves by...
Preprint
Full-text available
Goal-directed behavior depends on both motivational (“wanting”) and hedonic (“liking”) dimensions of rewards. Previous animal and human research linked wanting and liking to anatomically and neurochemically distinct brain mechanisms, but it remains unknown as to how the different brain regions and neurotransmitter systems interact in processing dis...
Article
Although it is widely accepted that the orbitofrontal cortex (OFC) is important for decision making, its precise contribution to behavior remains a topic of debate. While many loss of function experiments have been conducted in animals, causal studies of human OFC function are relatively scarce. This review discusses recent causal investigations in...
Article
Many decisions are guided by expectations about their outcomes. These expectations can arise from two fundamentally different sources: from direct experience with outcomes and the events and actions that precede them or from mental simulations and inferences when direct experience is missing. Here we discuss four elegant tasks from animal learning...
Article
The orbitofrontal cortex (OFC) plays a prominent role in signaling reward expectations. Two important features of rewards are their value (how good they are) and their specific identity (what they are). Whereas research on OFC has traditionally focused on reward value, recent findings point toward a pivotal role of reward identity in understanding...
Article
Episodic memory involves the reinstatement of distributed patterns of brain activity present when events were initially experienced. The hippocampus is thought to coordinate reinstatement via its interactions with a network of brain regions, but this hypothesis has not been causally tested in humans. The current study directly tested the involvemen...
Article
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...
Preprint
Full-text available
Episodic memory involves the reinstatement of distributed patterns of brain activity present when events were initially experienced. The hippocampus is thought to coordinate reinstatement via its interactions with a network of brain regions, but this hypothesis has not been causally tested in humans. The current study directly tested the involvemen...
Preprint
Full-text available
Decisions are typically guided by what we have experienced in the past. However, when direct experience is unavailable, animals and humans can imagine or infer the future to make choices. Outcome expectations that are based on direct experience and inference may compete for guiding behavior [1, 2], and they may recruit distinct but overlapping brai...
Article
Full-text available
Internal representations of relationships between events in the external world can be utilized to infer outcomes when direct experience is lacking. This process is thought to involve the orbitofrontal cortex (OFC) and hippocampus (HPC), but there is little evidence regarding the relative role of these areas and their interactions in inference. Here...
Article
Full-text available
Outcome-guided behavior requires knowledge about the current value of expected outcomes. Such behavior can be isolated in the reinforcer devaluation task, which assesses the ability to infer the current value of specific rewards after devaluation. Animal lesion studies demonstrate that orbitofrontal cortex (OFC) is necessary for normal behavior in...
Article
Full-text available
Dopamine neurons respond to errors in predicting value-neutral sensory information. These data, combined with causal evidence that dopamine transients support sensory-based associative learning, suggest that the dopamine system signals a multidimensional prediction error. Yet such complexity is not evident in individual neuron or average neural act...
Article
Full-text available
Sleep deprivation has marked effects on food intake, shifting food choices toward energy-dense options. Here we test the hypothesis that neural processing in central olfactory circuits, in tandem with the endocannabinoid system (ECS), plays a key role in mediating this relationship. We combined a partial sleep-deprivation protocol, pattern-based ol...
Preprint
Full-text available
Outcome-guided behavior requires knowledge about the current value of expected outcomes. Such behavior can be isolated in the reinforcer devaluation task, which assesses the ability to infer the current value of rewards after devaluation. Animal lesion studies demonstrate that orbitofrontal cortex (OFC) is necessary for normal behavior in this task...
Preprint
Full-text available
Dopamine neurons respond to errors in predicting value-neutral sensory information. These data, combined with causal evidence that dopamine transients support sensory-based associative learning, suggest that the dopamine system signals a multidimensional prediction error. Yet such complexity is not evident in individual neuron or average neural act...
Article
Full-text available
The central processing pathways of the human olfactory system are not fully understood. The olfactory bulb projects directly to a number of cortical brain structures, but the distinct networks formed by projections from each of these structures to the rest of the brain have not been well-defined. Here, we used functional magnetic resonance imaging...
Article
Full-text available
The firing of dopaminergic midbrain neurons is thought to reflect prediction errors (PE) that depend on the difference between the value of expected and received rewards. However, recent work has demonstrated that unexpected changes in value-neutral outcome features, such as identity, can evoke similar responses. It remains unclear whether the magn...
Article
Searching for food, friends, and mates often begins with an airborne scent. Importantly, odor concentration rises with physical proximity to an odorous source, suggesting a framework for orienting within olfactory landscapes to optimize behavior. Here, we created a two-dimensional odor space composed purely of odor stimuli to model how a navigator...
Article
Full-text available
Slow-wave sleep is an optimal opportunity for memory consolidation: when encoding occurs in the presence of a sensory cue, delivery of that cue during sleep enhances retrieval of associated memories. Recent studies suggest that cues might promote consolidation by inducing neural reinstatement of cue-associated content during sleep, but direct evide...
Article
Full-text available
The value of rewards arises from multiple hedonic and motivational dimensions. Reward-encoding brain regions such as the ventral striatum (VS) are known to process these dimensions. However, the mechanism whereby distinct reward dimensions are selected for neural processing and guiding behavior remains unclear. Here, we used functional imaging to i...
Data
Excel spreadsheet containing, in separate sheets, the underlying numerical data for Fig 1C, 1D and 1E; Fig 2B, 2C, 2E, 2F, 2H, 2I, 2K and 2L; and Fig 3B. (XLSX)
Article
Full-text available
Alterations in motivated behavior are a hallmark of attention-deficit/hyperactivity disorder (ADHD), one of the most common psychiatric disorders in children and adolescents. The orbitofrontal cortex (OFC) plays a key role in controlling goal-directed behavior, but the link between OFC dysfunction and behavioral deficits in ADHD, particularly in ad...
Article
Full-text available
There is general consensus that dopaminergic midbrain neurons signal reward prediction errors, computed as the difference between expected and received reward value. However, recent work in rodents shows that these neurons also respond to errors related to inferred value and sensory features, indicating an expanded role for dopamine beyond learning...
Article
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Memorable positive and negative experiences produce different profiles of gene expression in brain areas associated with long-term memory.
Article
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Generous behaviour is known to increase happiness, which could thereby motivate generosity. In this study, we use functional magnetic resonance imaging and a public pledge for future generosity to investigate the brain mechanisms that link generous behaviour with increases in happiness. Participants promised to spend money over the next 4 weeks eit...
Article
Information about potential rewards in the environment is essential for guiding adaptive behavior, and understanding neural reward processes may provide insights into neuropsychiatric dysfunctions. Over the past 10 years, multivoxel pattern analysis (MVPA) techniques have been used to study brain areas encoding information about expected and experi...
Article
Full-text available
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 (i.e., cognitive maps), including a conjunction of expected reward identity and value. Here we tested how identity-specific representations of food...
Article
Significance statement: A key role of any neuromodulator may be the reconfiguration of functional brain circuits. Here we test this idea with regard to dopamine and the organization of functional networks in the OFC. We show that blockade of dopamine D2-receptors has profound effects on the functional connectivity patterns of the OFC, yielding in...
Chapter
Value and salience are key variables for associative learning, decision-making, and attention. In this chapter we review definitions of value and salience, and describe human neuroimaging studies that dissociate these variables. Value increases with the magnitude and probability of reward but decreases with the magnitude and probability of punishme...
Article
Full-text available
The spinal cord is the first site of nociceptive processing in the central nervous system and has a role in the development and perpetuation of clinical pain states. Advancements in functional magnetic resonance imaging are providing a means to non-invasively measure spinal cord function, and functional magnetic resonance imaging may provide an obj...
Article
Full-text available
Perceptually similar stimuli often predict vastly different outcomes, requiring the brain to maintain specific associations in the face of potential ambiguity. This could be achieved either through local changes in stimulus representations, or through modulation of functional connections between stimulus-coding and outcome-coding regions. Here we t...
Data
Supplementary Figures 1-4 and Supplementary Tables 1-2
Article
The ability to generalize previously learned information to novel situations is fundamental for adaptive behavior. However, too wide or too narrow generalization is linked to neuropsychiatric disorders. Previous research suggests that interactions between the dopaminergic system and the hippocampus may play a role in generalization, but whether and...
Article
Full-text available
Unlabelled: 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 represe...
Article
Full-text available
Rewards obtained from specific behaviors can and do change across time. To adapt to such conditions, humans need to represent and update associations between behaviors and their outcomes. Much previous work focused on how rewards affect the processing of specific tasks. However, abstract associations between multiple potential behaviors and multipl...
Article
Full-text available
Deficits in impulse control are discussed as key mechanisms for major worldwide health problems such as drug addiction and obesity. For example, obese subjects have difficulty controlling their impulses to overeat when faced with food items. Here, we investigated the role of neural impulse control mechanisms for dietary success in middle-aged obese...
Article
Full-text available
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 s...
Article
Full-text available
Value-based decisions optimize the relation of costs and benefits. Costs and benefits confer not only value but also salience, which may influence decision making through attentional mechanisms. However, the computational and neurobiological role of salience in value-based decisions remains elusive. Here we develop and contrast two formal concepts...
Article
Full-text available
The primate orbitofrontal cortex (OFC) is involved in reward processing, learning, and decision making. Research in monkeys has shown that this region is densely connected with higher sensory, limbic, and subcortical regions. Moreover, a parcellation of the monkey OFC into two subdivisions has been suggested based on its intrinsic anatomical connec...
Article
Zusammenfassung Seit dem Aufkommen der funktionellen Magnetresonanztomografie (fMRT) vor 20 Jahren steht eine neue Methode zur nicht invasiven Messung von Gehirnfunktionen zur Verfügung, welche in den kognitiven Neurowissenschaften inzwischen weit verbreitet ist. Traditionell wurden fMRT-Daten vor allem verwendet, um globale Änderungen der Aktivitä...
Article
Full-text available
To efficiently represent all of the possible rewards in the world, dopaminergic midbrain neurons dynamically adapt their coding range to the momentarily available rewards. Specifically, these neurons increase their activity for an outcome that is better than expected and decrease it for an outcome worse than expected, independent of the absolute re...
Article
Full-text available
The advent of functional magnetic resonance imaging (fMRI) of brain function 20 years ago has provided a new methodology for non-invasive measurement of brain function that is now widely used in cognitive neuroscience. Traditionally, fMRI data has been analyzed looking for overall activity changes in brain regions in response to a stimulus or a cog...
Article
Full-text available
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. Howeve...
Article
Full-text available
During development, children improve in learning from feedback to adapt their behavior. However, it is still unclear which neural mechanisms might underlie these developmental changes. In the current study, we used a reinforcement learning model to investigate neurodevelopmental changes in the representation and processing of learning signals. Sixt...
Article
Full-text available
Everyday choice options have advantages (positive values) and disadvantages (negative values) that need to be integrated into an overall subjective value. For decades, economic models have assumed that when a person evaluates a choice option, different values contribute independently to the overall subjective value of the option. However, human cho...
Article
In everyday life, successful decision making requires precise representations of expected values. However, for most behavioral options more than one attribute can be relevant in order to predict the expected reward. Thus, to make good or even optimal choices the reward predictions of multiple attributes need to be integrated into a combined expecte...
Article
Full-text available
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 b...