errors-as-a-means-of-reducing-impulsive-food-choice

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 ...

Choices are often intertemporal, requiring tradeoff of short-term and long-term outcomes. In such contexts, humans may prefer small rewards delivered immediately to larger rewards delivered after a delay, reflecting temporal discounting (TD) of delayed outcomes. The medial orbitofrontal cortex (mOFC) is consistently activated during intertemporal choice, yet its role remains unclear. Here, patients with lesions in the mOFC (mOFC patients), control patients with lesions outside the frontal lobe, and healthy individuals chose hypothetically between small-immediate and larger-delayed rewards. The type of reward varied across three TD tasks, including both primary (food) and secondary (money and discount vouchers) rewards. We found that damage to mOFC increased significantly the preference for small-immediate over larger-delayed rewards, resulting in steeper TD of future rewards in mOFC patients compared with the control groups. This held for both primary and secondary rewards. All participants, including mOFC patients, were more willing to wait for delayed money and discount vouchers than for delayed food, suggesting that mOFC patients' (impatient) choices were not due merely to poor motor impulse control or consideration of the goods at stake. These findings provide the first evidence in humans that mOFC is necessary for valuation and preference of delayed rewards for intertemporal choice.

Myopic discounting of future rewards after medial orbitofrontal damage in humans.

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).

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

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.

Investment and repayment in a trust game after ventromedial prefrontal damage.

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.

Errors affect hypothetical intertemporal food choice in women.

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.

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

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.

Article	Year
Myopic discounting of future rewards after medial orbitofrontal damage in humans. The Journal of neuroscience : the official journal of the Society for Neuroscience\| PubMed ID: 21147982	2010
The neurobiology of intertemporal choice: insight from imaging and lesion studies. Reviews in the neurosciences\| PubMed ID: 21967518	2011
Investment and repayment in a trust game after ventromedial prefrontal damage. Frontiers in human neuroscience\| PubMed ID: 24093013	2013
Errors affect hypothetical intertemporal food choice in women. PloS one\| PubMed ID: 25244534	2014
Impulsivity toward food reward is related to BMI: Evidence from intertemporal choice in obese and normal-weight individuals. Brain and cognition\| PubMed ID: 26525096	2015
Reduced Sensitivity to Sooner Reward During Intertemporal Decision-Making Following Insula Damage in Humans. Frontiers in behavioral neuroscience\| PubMed ID: 26793084	2015

Manuela Sellitto

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