Manuela Sellitto

The neurobiology of intertemporal choice: insight from imaging and lesion studies

Abstract People are frequently faced with intertemporal choices, i.e., choices differing in the timing of their consequences, preferring smaller rewards available immediately over larger rewards delivered after a delay. The inability to forgo sooner gratification to favor delayed reward (e.g., impulsivity) has been related to several pathological conditions characterized by poor self-control, including drug addiction and obesity. Comparative and functional human studies have implicated a network of brain areas involved in intertemporal choice, including the medial portion of the orbitofrontal cortex (mOFC). Moreover, damage to this cortical area increases preference for immediate gratification in intertemporal decisions. Here, we review recent neuroscientific studies concerning intertemporal choice, suggesting that the mOFC contributes to preference for delayed rewards, either by computing the value of future outcomes (i.e., valuation), or by enabling people to imagine and represent future rewards and their consequences (e.g., prospection).

Impulsivity toward food reward is related to BMI: Evidence from intertemporal choice in obese and normal-weight individuals.

Obesity is a medical condition frequently associated with psychopathological symptoms and neurocognitive and/or personality traits related to impulsivity. Impulsivity during intertemporal choices seems to be typical of obese individuals. However, so far, the specific relationship between different types of reward and neuropsychological and psychopathological profile are yet to be unravelled. Here, we investigated impulsive choice for primary and secondary reward in obese individuals and normal-weight controls with comparable neuropsychological and psychopathological status. Participants performed three intertemporal choice tasks involving food, money, and discount voucher, respectively. Moreover, they completed a battery of neuropsychological tests and psychometric questionnaires assessing psychopathological state, impulsivity, and personality traits. Obese individuals showed increased preference for immediate food reward compared with controls, whereas no group difference emerged concerning money and discount voucher. Moreover, the higher the body mass index (BMI), the steeper the food discounting. These findings emerged in light of comparable neuropsychological and psychopathological profile between groups. Steeper food discounting in obese individuals appears to be related to BMI but not to psychopathological and neuropsychological profile. We suggest using intertemporal choice in the clinical practice as measure of the effectiveness of different types of intervention (e.g., educational, psychological, pharmacological or surgical) aimed at reducing impulsivity toward food and increasing cognitive control during food intake in obese individuals.

Investment and repayment in a trust game after ventromedial prefrontal damage

Although trust and reciprocity are ubiquitous in social exchange, their neurobiological substrate remains largely unknown. Here, we investigated the effect of damage to the ventromedial prefrontal cortex (vmPFC)—a brain region critical for valuing social information—on individuals’ decisions in a trust game and in a risk game. In the trust game, one player, the investor, is endowed with a sum of money, which she can keep or invest. The amount she decides to invest is tripled and sent to the other player, the trustee, who then decides what fraction to return to the investor. In separate runs, ten patients with focal bilateral damage to the vmPFC and control participants made decision while playing in the role of either investor or trustee with different anonymous counterparts in each run. A risk game was also included in which the investor faced exactly the same decisions as in the trust game, but a random device (i.e., a computer), not another player, determined the final payoffs. Results showed that vmPFC patients’ investments were not modulated by the type of opponent player (e.g., human vs. computer) present in the environment. Thus, vmPFC patients showed comparable risk-taking preferences both in social (trust game) and nonsocial (risk game) contexts. In stark contrast, control participants were less willing to take risk and invest when they believed that they were interacting with people than a computer. Furthermore, when acted as trustee, vmPFC patients made lower back transfers toward investors, thereby showing less reciprocity behavior. Taken together, these results indicate that social valuation and emotion subserved by vmPFC have a critical role in trusting and reciprocity decisions. The present findings support the hypothesis that vmPFC damage may impair affective systems specifically designed for mediating social transaction with other individuals.

Reduced Sensitivity to Sooner Reward During Intertemporal Decision-Making Following Insula Damage in Humans.

During intertemporal choice, humans tend to prefer small-sooner rewards over larger-delayed rewards, reflecting temporal discounting (TD) of delayed outcomes. Functional neuroimaging (fMRI) evidence has implicated the insular cortex in time-sensitive decisions, yet it is not clear whether activity in this brain region is crucial for, or merely associated with, TD behavior. Here, patients with damage to the insula (Insular patients), control patients with lesions outside the insula, and healthy individuals chose between smaller-sooner and larger-later monetary rewards. Insular patients were less sensitive to sooner rewards than were the control groups, exhibiting reduced TD. A Voxel-based Lesion-Symptom Mapping (VLSM) analysis confirmed a statistically significant association between insular damage and reduced TD. These results indicate that the insular cortex is crucial for intertemporal choice. We suggest that he insula may be necessary to anticipate the bodily/emotional effects of receiving rewards at different delays, influencing the computation of their incentive value. Devoid of such input, insular patients’ choices would be governed by a heuristic of quantity, allowing patients to wait for larger options.

Errors Affect Hypothetical Intertemporal Food Choice in Women

Growing evidence suggests that the ability to control behavior is enhanced in contexts in which errors are more frequent. Here we investigated whether pairing desirable food with errors could decrease impulsive choice during hypothetical temporal decisions about food. To this end, healthy women performed a Stop-signal task in which one food cue predicted high-error rate, and another food cue predicted low-error rate. Afterwards, we measured participants’ intertemporal preferences during decisions between smaller-immediate and larger-delayed amounts of food. We expected reduced sensitivity to smaller-immediate amounts of food associated with high-error rate. Moreover, taking into account that deprivational states affect sensitivity for food, we controlled for participants’ hunger. Results showed that pairing food with high-error likelihood decreased temporal discounting. This effect was modulated by hunger, indicating that, the lower the hunger level, the more participants showed reduced impulsive preference for the food previously associated with a high number of errors as compared with the other food. These findings reveal that errors, which are motivationally salient events that recruit cognitive control and drive avoidance learning against error-prone behavior, are effective in reducing impulsive choice for edible outcomes.

Now or not-now? The influence of alexithymia on intertemporal decision-making

HIGHLIGHTSIntertemporal choices arise from the balance between visceral and rational components.Alexithymic behave more impatiently than not‐alexithymic in intertemporal decisions.In alexithymia the sensitivity to visceral sensations correlates with impatience.Disproportionate valuation of reward available immediately is observed in alexithymia.This reflect alexithymic heightened perception of bodily physiological signals. ABSTRACT Optimal intertemporal decisions arise from the balance between an emotional‐visceral component, signaling the need for immediate gratification, and a rational, long‐term oriented component. Alexithymia, a personality construct characterized by amplified sensitivity to internal bodily signals of arousal, may result in enhanced activation of the emotional‐visceral component over the cognitive‐rational one. To test this hypothesis, participants with high‐ and low‐alexithymia level were compared at an intertemporal decision‐making task, and their choice behavior correlated with their interoceptive sensitivity. We show that high‐alexithymic tend to behave more impatiently than low‐alexithymic in intertemporal decisions, particularly when the sooner reward is immediately available. Moreover, the greater their sensitivity to their own visceral sensations, the greater the impatience. Together, these results suggest a disproportionate valuation of reward available immediately in high alexithymia, possibly reflecting heightened perception of bodily physiological signals, which ultimately would bias their intertemporal decision‐making.

Multiple sclerosis reduces sensitivity to immediate reward during decision making.

Individuals with multiple sclerosis (MS) often face important health-related and financial decisions that involve trade-offs between short-term and long-term benefits, yet decision making is rarely studied in MS patients. The temporal discounting paradigm is a useful tool for investigating such time-dependent choices in humans. Here, we investigated whether patients with relapsing-remitting MS differed from healthy controls when making choices between hypothetical monetary rewards available at different points in time. Participants were tested in two conditions: in one, the choice was between a smaller amount of money available immediately and a larger amount of money available at a later date; in the other, a fixed delay of 60 days was added to both options. We found that, compared with healthy controls, MS patients favored less the sooner reward in the condition involving an immediate reward, whereas no difference between MS patients and the control group emerged in the condition involving only delayed rewards. Moreover, the decreased immediacy bias was corroborated by lower scores at scale that assesses responsiveness to rewards in MS patients. Taken together, these findings indicate reduced sensitivity to immediate reward and a consequent stronger willingness to defer gratification in MS individuals.

Errors as a Means of Reducing Impulsive Food Choice

Nowadays, the increasing incidence of eating disorders due to poor self-control has given rise to increased obesity and other chronic weight problems, and ultimately, to reduced life expectancy. The capacity to refrain from automatic responses is usually high in situations in which making errors is highly likely. The protocol described here aims at reducing imprudent preference in women during hypothetical intertemporal choices about appetitive food by associating it with errors. First, participants undergo an error task where two different edible stimuli are associated with two different error likelihoods (high and low). Second, they make intertemporal choices about the two edible stimuli, separately. As a result, this method decreases the discount rate for future amounts of the edible reward that cued higher error likelihood, selectively. This effect is under the influence of the self-reported hunger level. The present protocol demonstrates that errors, well known as motivationally salient events, can induce the recruitment of cognitive control, thus being ultimately useful in reducing impatient choices for edible commodities.

Attention, Neural Basis of

Typically, our environment contains many different objects, but the capacity of our nervous system to fully analyze them is limited. At any given time, only a small amount of the total sensory input is actively taken up for further processing. Several lines of evidence indicate that multiple object representations compete for processing resources in a mutually suppressive fashion. These competitive interactions take place in multiple brain systems, sensory and motor, and can be biased in favor of relevant information as a result of selective attention. Selective mechanisms appear to operate as top-down signals that modulate sensory processing in several ways: enhancement of neural response to an attended stimulus, suppression of ignored-object representations, and shift of baseline activity in the absence of sensory stimulation. Depending on the current task, spatial and nonspatial features can be used to give a competitive advantage and processing resources to objects of relevance. A main source of top-down biasing influence may derive from frontal and parietal structures involved in working memory and motor preparation.