Separate Neural Networks for Gains and Losses in Intertemporal Choice

The sign effect in temporal discounting does not require the hippocampus

When considering future outcomes, humans tend to discount gains more than losses. This phenomenon, referred to as the temporal discounting sign effect, is thought to result from the greater anticipated emotional impact of waiting for a negative outcome (dread) compared to waiting for a positive outcome (mixture of savoring and impatience). The impact of such anticipatory emotions has been proposed to rely on episodic future thinking. We evaluated this proposal by examining the presence and magnitude of a sign effect in the intertemporal decisions of individuals with hippocampal amnesia, who are severely impaired in their ability to engage in episodic mental simulation, and by comparing their patterns of choices to those of healthy controls. We also measured loss aversion, the tendency to assign greater value to losses compared to equivalent gains, to verify that any reduction in the sign effect in the hippocampal lesion group could not be explained by a group difference in loss aversion. Results showed that participants with hippocampal amnesia exhibited a sign effect, with less discounting of monetary losses compared to gains, that was similar in magnitude to that of controls. Loss aversion, albeit greater in the hippocampal compared to the control group, did not account for the sign effect. These results indicate that the sign effect does not depend on the integrity of hippocampally mediated episodic processes. They suggest instead that the impact of anticipatory emotions can be factored into decisions via semantic future thinking, drawing on non-contextual knowledge about oneself.

Impact of self-control and time perception on intertemporal choices in gain and loss situations

Individuals frequently encounter dilemmas in which they must choose between smaller, immediate gains and larger, delayed rewards; this phenomenon is known as intertemporal choice. The present study analyzed the interplay of trait and state self-control and time perception tendencies (time overestimation vs. time underestimation) and how it influences the rates of selecting immediate options in both gain and loss situations by conducting an intertemporal choice task. Experiment 1 was used to explore the impact of trait self-control and time perception on intertemporal choices within gain and loss situations. In Experiment 2, the e-crossing task was used to induce self-control resource depletion in participants and to investigate the impact of self-control resources and time perception on intertemporal choices in gain and loss situations. The results indicate that (1) compared with the high-self-control group, the low-self-control group exhibited a greater tendency to choose immediate options. Additionally, the high time estimation group was more likely to opt for immediate choices than the low time estimation group was. Furthermore, participants were more likely to select immediate options in the loss situation than in the gain situation. (2) In the gain situation, the high time estimation group was more likely to choose immediate options than was the low time estimation group. However, in the loss situation, the difference between the two groups was nonsignificant. (3) Time perception and gain-loss situations exerted a moderating mediating effect on the impact of self-control resources on intertemporal choices. These findings shed light on the influence of both self-control abilities and self-control resources on intertemporal choices. They provide valuable insights into intertemporal decision behaviors across diverse contexts and indicate the need for rational analysis based on one's current state to mitigate cognitive biases to ensure individuals can maximize benefits in their daily lives.

Posterior parietal cortex is causally involved in reward valuation but not in probability weighting during risky choice

This study provides evidence that the posterior parietal cortex is causally involved in risky decision making via the processing of reward values but not reward probabilities. In the within-group experimental design, participants performed a binary lottery choice task following transcranial magnetic stimulation of the right posterior parietal cortex, left posterior parietal cortex, and a right posterior parietal cortex sham (placebo) stimulation. The continuous theta-burst stimulation protocol supposedly downregulating the cortical excitability was used. Both, mean-variance and the prospect theory approach to risky choice showed that the posterior parietal cortex stimulation shifted participants toward greater risk aversion compared with sham. On the behavioral level, after the posterior parietal cortex stimulation, the likelihood of choosing a safer option became more sensitive to the difference in standard deviations between lotteries, compared with sham, indicating greater risk avoidance within the mean-variance framework. We also estimated the shift in prospect theory parameters of risk preferences after posterior parietal cortex stimulation. The hierarchical Bayesian approach showed moderate evidence for a credible change in risk aversion parameter toward lower marginal reward value (and, hence, lower risk tolerance), while no credible change in probability weighting was observed. In addition, we observed anecdotal evidence for a credible increase in the consistency of responses after the left posterior parietal cortex stimulation compared with sham.

The effects of materialism and ego depletion on intertemporal choice: An event-related potential study

Objective

The study aims to promote human beings to make scientific and reasonable decisions for the long-term and beautiful future.

Methods

We designed two experiments to explore the influence of materialism and ego depletion from the perspective of behavioral decision-making and neural mechanism.

Results

In Experiment 1, there was asymmetry in intertemporal choice between gain and loss situations. In the gain situation, high materialism were more likely to choose the later and larger option (LL). However, in a loss situation, we found a reverse sign effect, and the proportion of subjects choosing sooner and smaller options (SS) increased. In Experiment 2, in the gain situation, after adding the low ego depletion task, there was a marginal significant difference between high and low materialism in the percentage of choosing LL options, F(1, 40) = 3.37, P = 0.07, η² = 0.08; After adding the high ego depletion task, the percentage of choosing LL options was no difference, F(1, 40) = 1.42, P > 0.05. In the loss situation, whether in the high ego depletion task [F(1, 40) = 2.25, P > 0.05) or in the low ego depletion task [F(1, 40) = 1.44, P > 0.05), there was no difference between high and low materialism in the percentage of choosing LL options, and they both tended to choose SS options. The EEG study showed that in high materialism, there was a significant difference between the high and low ego depletion conditions, and the N1 amplitude induced under the low ego depletion condition was larger than that under the high ego depletion condition. However, there was no significant difference in N1 amplitude between the high and low ego depletion conditions in the low materialism. The amplitude of P2 evoked in the loss situation was larger than that in the gain situation.

Conclusion

In conclusion, Materialism dominated people's intertemporal choices, and ego depletion affected the intertemporal choice to a certain extent by influencing the subjects' thinking activities. The COVID-19 epidemic maybe affected intertemporal choice indirectly by acting on materialistic values and subjects' emotions.

The effect of incentives on intertemporal choice: Choice, confidence, and eye movements

Despite various studies examining intertemporal choice with hypothetical rewards due to problematic real reward delivery, there remains no substantial evidence on the effect of the incentives on the decision confidence and cognitive process in intertemporal choice and no comprehensive exploration on the loss domain. Hence, this study conducts an eye-tracking experiment to examine the effect of incentive approach and measure participants' decision confidence using a between-subject design in both gain and loss domains. Results replicated previous findings which show incentives do not affect intertemporal choice in the gain domain. In contrast, in the loss domain, participants in the incentivized group were more likely to choose the larger-later options than those in the non-incentivized group. Furthermore, the decision confidence and the mean fixation duration differed between the incentivized and non-incentivized groups in both gain and loss domains. These findings allow for a better understanding of the effect of incentives on intertemporal choice and provide valuable information for the design of incentives in future intertemporal experiments.

A neuro-computational account of procrastination behavior

Humans procrastinate despite being aware of potential adverse consequences. Yet, the neuro-computational mechanisms underlying procrastination remain poorly understood. Here, we use fMRI during intertemporal choice to inform a computational model that predicts procrastination behavior in independent tests. Procrastination is assessed in the laboratory as the preference for performing an effortful task on the next day as opposed to immediately, and at home as the delay taken in returning completed administrative forms. These procrastination behaviors are respectively modeled as unitary and repeated decisions to postpone a task until the next time step, based on a net expected value that integrates reward and effort attributes, both discounted with delay. The key feature that is associated with procrastination behavior across individuals (both in-lab and at-home) is the extent to which the expected effort cost (signaled by the dorsomedial prefrontal cortex) is attenuated by the delay before task completion. Thus, procrastination might stem from a cognitive bias that would make doing a task later (compared to now) appear as much less effortful but not much less rewarding.

Most humans procrastinate to some extent, despite adverse consequences. Here, the authors show that how much an individual procrastinates, both in the lab and at home, relates to brain signals that reflect temporal discounting of effort cost.

Comparing Discounting of Potentially Real Rewards and Losses by Means of Functional Magnetic Resonance Imaging

Aim

Delay discounting (DD) has often been investigated in the context of decision making whereby individuals attribute decreasing value to rewards in the distant future. Less is known about DD in the context of negative consequences. The aim of this pilot study was to identify commonalities and differences between reward and loss discounting on the behavioral as well as the neural level by means of computational modeling and functional Magnetic Resonance Imaging (fMRI). We furthermore compared the neural activation between anticipation of rewards and losses.

Method

We conducted a study combining an intertemporal choice task for potentially real rewards and losses (decision-making) with a monetary incentive/loss delay task (reward/loss anticipation). Thirty healthy participants (age 18-35, 14 female) completed the study. In each trial, participants had to choose between a smaller immediate loss/win and a larger loss/win at a fixed delay of two weeks. Task-related brain activation was measured with fMRI.

Results

Hyperbolic discounting parameters of loss and reward conditions were correlated (r = 0.56). During decision-making, BOLD activation was observed in the parietal and prefrontal cortex, with no differences between reward and loss conditions. During reward and loss anticipation, dissociable activation was observed in the striatum, the anterior insula and the anterior cingulate cortex.

Conclusion

We observed behavior concurrent with DD in both the reward and loss condition, with evidence for similar behavioral and neural patterns in the two conditions. Intertemporal decision-making recruited the fronto-parietal network, whilst reward and loss anticipation were related to activation in the salience network. The interpretation of these findings may be limited to short delays and small monetary outcomes.

Inhibitory Effect of Aptamer-Carbon Dot Nanomaterial-siRNA Complex on the Metastasis of Hepatocellular Carcinoma Cells by Interfering with FMRP

Using small interfering RNA (siRNA) for the specific gene-silencing has been a novel therapeutic method for the treatment of incurable diseases such as malignancies. However, it remains a challenge whether siRNA can be safely and effectively delivered into target cells. Therefore, we synthesized fluorescent carbon dots (CDs) as a gene vector at the siRNA delivery system that induced efficient gene knockdown in vitro while binding aptamer AS1411 to resolve the difficulty in cell targeting. We found that CDs with adequate biocompatibility can improve the efficiency of cellular uptake of siRNA. CLSM and FCM results showed that CDs were mainly localized in the cytoplasm and emitted bright green fluorescence. In addition, the CD/siRNA delivery system mediated by the aptamer AS1411 effectively silenced the expression of Fragile X mental retardation protein (FMRP) and successfully inhibited the migration and invasive propensity of hepatocellular carcinoma (HCC) cells. In summary, we have synthesized a valuable siRNA delivery vector enabling not only bioimaging but also effective downregulation of gene expression, which is indicative of an efficient potential for gene delivery and therapy.

Reduced sensitivity to delayed time and delayed reward of the post-operative insular glioma patients in delay discounting

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The behavior study exhibited post-operative insular glioma patients performed a reduced sensitivity of delayed time and delayed reward in delay discounting task.

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The fMRI study in healthy subjects revealed the insula associated with delayed time, delayed reward processing, which could contribute to the patients’ behavior.

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Combined with these two studies, our results provided evidences that the insula involved in delay discounting, and patients underwent insular glioma surgery could have an impaired delay discounting performance.

Previous studies have shown that the insula is closely related to addiction, and the structure’s role in delay discounting can be measured by a specific task, but the specific role of the insula has been less studied. In this study, we first conducted a lesion study in which we recruited healthy controls (n = 30) and patients with unilateral insula injury (n = 16) to complete a behavioral delay discounting task. Then we conducted a functional magnetic resonance imaging (fMRI) study, and a separate group healthy volunteers (n = 51) completed a delay discounting task during the fMRI scan. The lesion study showed a significant difference between the two groups in the delay discounting task, which revealed that insula injury was associated with impaired decision making. The fMRI study revealed choice-sensitive insula activation that was modulated by delayed time and delayed reward, indicating an important role of the insula in delay discounting. Overall, our results provide evidence for a role of the insular lobe in delay discounting and suggests that this structure may be considered an important factor in the future treatment and diagnosis of addiction disorders.

Music-induced emotions influence intertemporal decision making

People tend to choose smaller, immediate rewards over larger, delayed rewards. This phenomenon is thought to be associated with emotional engagement. However, few studies have demonstrated the real-time impact of incidental emotions on intertemporal choices. This research investigated the effects of music-induced incidental emotions on intertemporal choices, during which happy or sad music was played simultaneously. We found that music-induced happiness made participants prefer smaller-but-sooner rewards (SS), whereas music-induced sadness made participants prefer larger-but-later rewards (LL). Time perception partially mediated this effect: the greater the perceived temporal difference, the more likely they were to prefer SS. Tempo and mode were then manipulated to disentangle the effects of arousal and mood on intertemporal choices. Only tempo-induced arousal, but not mode-induced mood, affected intertemporal choices. These results suggest the role of arousal in intertemporal decision making and provide evidence in support of equate-to-differentiate theory with regard to the non-compensatory mechanism in intertemporal choices.

Arbitration between insula and temporoparietal junction subserves framing-induced boosts in generosity during social discounting

Generosity toward others declines across the perceived social distance to them. Here, participants chose between selfish and costly generous options in two conditions: in the gain frame, a generous choice yielded a gain to the other; in the loss frame, it entailed preventing the loss of a previous endowment to the other. Social discounting was reduced in the loss compared to the gain frame, implying increased generosity toward strangers. Using neuroimaging tools, we found that while activity in the temporoparietal junction (TPJ) and the ventromedial prefrontal cortex (VMPFC) was associated with generosity in the gain frame, the insular cortex was selectively recruited during generous choices in the loss frame. We provide support for a network-model according to which TPJ and insula differentially subserve generosity by modulating value signals in the VMPFC in a frame-dependent fashion. These results extend our understanding of the insula role in nudging prosocial behavior in humans.

Hierarchical Neural Prediction of Interpersonal Trust

Exploring neural markers that predict trust behavior may help us to identify the cognitive process underlying trust decisions and to develop a new approach to promote interpersonal trust. It remains unknown how trust behavior may be predicted early in the decision process. We used electrophysiology to sample the brain activity while participants played the role of trustor in an iterative trust game. The results showed that during the trust generation stage, the trust condition led to higher frontocentral beta band activity related to cognitive inhibition compared to the distrust condition (item level). Moreover, individuals with higher frontocentral beta band activity were more likely to perform trust choices at the single-trial level (individual level). Furthermore, after receiving reciprocity feedback on trial_n-1, compared to the betrayal feedback and the distrust choice, the frontocentral beta band oscillation had a stronger predictive effect regarding trust choices on trial_n. These findings indicate that beta band oscillations during the decision generation stage contribute to subsequent trust choices.

Brain-wide Mapping of Mono-synaptic Afferents to Different Cell Types in the Laterodorsal Tegmentum

The laterodorsal tegmentum (LDT) is a brain structure involved in distinct behaviors including arousal, reward, and innate fear. How environmental stimuli and top-down control from high-order sensory and limbic cortical areas converge and coordinate in this region to modulate diverse behavioral outputs remains unclear. Using a modified rabies virus, we applied monosynaptic retrograde tracing to the whole brain to examine the LDT cell type specific upstream nuclei. The LDT received very strong midbrain and hindbrain afferents and moderate cortical and hypothalamic innervation but weak connections to the thalamus. The main projection neurons from cortical areas were restricted to the limbic lobe, including the ventral orbital cortex (VO), prelimbic, and cingulate cortices. Although different cell populations received qualitatively similar inputs, primarily via afferents from the periaqueductal gray area, superior colliculus, and the LDT itself, parvalbumin-positive (PV⁺) GABAergic cells received preferential projections from local LDT neurons. With regard to the different subtypes of GABAergic cells, a considerable number of nuclei, including those of the ventral tegmental area, central amygdaloid nucleus, and VO, made significantly greater inputs to somatostatin-positive cells than to PV⁺ cells. Diverse inputs to the LDT on a system-wide level were revealed.

Modulation of Beta Oscillations for Implicit Motor Timing in Primate Sensorimotor Cortex during Movement Preparation

Motor timing is an important part of sensorimotor control. Previous studies have shown that beta oscillations embody the process of temporal perception in explicit timing tasks. In contrast, studies focusing on beta oscillations in implicit timing tasks are lacking. In this study, we set up an implicit motor timing task and found a modulation pattern of beta oscillations with temporal perception during movement preparation. We trained two macaques in a repetitive visually-guided reach-to-grasp task with different holding intervals. Spikes and local field potentials were recorded from microelectrode arrays in the primary motor cortex, primary somatosensory cortex, and posterior parietal cortex. We analyzed the association between beta oscillations and temporal interval in fixed-duration experiments (500 ms as the Short Group and 1500 ms as the Long Group) and random-duration experiments (500 ms to 1500 ms). The results showed that the peak beta frequencies in both experiments ranged from 15 Hz to 25 Hz. The beta power was higher during the hold period than the movement (reach and grasp) period. Further, in the fixed-duration experiments, the mean power as well as the maximum rate of change of beta power in the first 300 ms were higher in the Short Group than in the Long Group when aligned with the Center Hit event. In contrast, in the random-duration experiments, the corresponding values showed no statistical differences among groups. The peak latency of beta power was shorter in the Short Group than in the Long Group in the fixed-duration experiments, while no consistent modulation pattern was found in the random-duration experiments. These results indicate that beta oscillations can modulate with temporal interval in their power mode. The synchronization period of beta power could reflect the cognitive set maintaining working memory of the temporal structure and attention.

Neurobiology and clinical features of impulse control failure in Parkinson's disease

Impulse control disorders (ICDs) and other impulsive-compulsive related behaviours are frequent and still under recognized non-motor complications of Parkinson's disease (PD). They result from sensitization of the mesocorticolimbic pathway that arose in predisposed PD patients concomitantly with spreading of PD pathology, non-physiological dopaminergic and pulsatile administration of dopamine replacement therapy (DRT). Neuropsychiatric fluctuations (NPF) reflect the psychotropic effects of dopaminergic drugs and play a crucial role in the emergence of ICDs and behavioral addictions. Dopamine agonists (DA) which selectively target D2 and D3 receptors mostly expressed within the mesocorticolimbic pathway, are the main risk factor to develop ICDs. Neuroimaging studies suggest that dopamine agonists lead to a blunted response of the brain's reward system both during reward delivery and anticipation. Genetic predispositions are crucial for the responsiveness of the mesolimbic system and the development of ICDs with several genes having been identified. Early screening for neuropsychiatric fluctuations, reduction of DA, fractionating levodopa dosage, education of patients and their relatives, are the key strategies for diagnosis and management of ICDs and related disorders.