999 research outputs found
sj-docx-1-pss-10.1177_09567976221082637 – Supplemental material for Choice Boosts Curiosity
No full textSupplemental material, sj-docx-1-pss-10.1177_09567976221082637 for Choice Boosts Curiosity by Patricia Romero Verdugo, Lieke L. F. van Lieshout, Floris P. de Lange and Roshan Cools in Psychological Science</p
Effects of dopaminergic medication on reward and punishment sensitivity in risky decision-making
No full textPathological gambling (PG) is a behavioural addiction similar in many aspects to substance use disorder (Clark & Limbrick-Oldfield, 2014). PG involves excessive risk taking and (monetary) reward. Neurotransmitter dopamine is of interest in relation to risk taking and PG due to its central role in learning from reward and punishment (Cools et al., 2009). Moreover, some Parkinson’s disease patients develop PG following dopamine replacement therapy (Clark & Dagher, 2014). The aim of this study was to examine the effects of dopaminergic modulation on risk-taking behaviour in healthy and PG individuals. Dopamine D2/D3 receptor antagonist sulpiride and a placebo drug were administered in order to transiently alter dopamine transmission during an economic decision-making task. Participants chose between sure choices of winning (or losing) a certain amount of money and gambles with different probabilities to win (or lose) money. A prospect theory (Kahneman & Tversky, 1979) modelling approach was used to estimate parameters reflecting sensitivity to outcomes and probabilities and optimism about risk, based on the varying amounts of money and probabilities in the task. We found that sulpiride decreased distortion in weighting the probabilities of potential gains. That is, participants overweighted low and underweighted moderate to high winning probabilities less under sulpiride compared with placebo. However, the drug effect did not differ between the groups and was not found in the loss domain. In conclusion, we found evidence for a relationship between dopamine and risky decision-making in the distortion of probability weighting
Modulating flexible and stable cognitive control: Does a high reward context bias a person into a more flexible state over a stable state?
No full textCognitive control has proven to be both limited and demanding, and is suggested to acquire a certain cost (Posner, & Snyder, 1975; Botvinick, & Braver, 2014). If cognitive control is costly, this raises the question what this cost entails and what mechanism underlies it. Different researchers have suggested that the feeling of cost or feeling of effort associated with implementing cognitive control is a result of an opportunity cost, which can be represented by the average reward rate of the environment (Kurzban, Duckworth, Kable, & Meyers, 2013; Constantino, & Daw, 2015). Research has suggested that the feeling of opportunity cost facilitates exploration versus exploitation, which could be translated to flexibility and stability in cognitive control. If the world is more volatile, being able to adapt quickly (flexibility) instead of focusing on one thing (stability) will be more beneficial for gaining maximum reward. That is why Cools (2006) suggests that an increase in opportunity cost could bias a person into a more flexible and less stable state through an increase of dopamine in the striatum. In our study, we investigated the hypothesis that a high reward context biases a person into a more flexible state over a stable state by manipulating the reward context in a working memory task. We investigated the effect of this manipulation on flexible and stable performance and on the subjective feeling of effort that was attributed to the two types of control. In addition, we explored the hypothesis that that the explore/exploit trade-off in foraging and the flexibility/stability trade-off in cognitive control are governed by the same mechanism. Results showed no evidence for an effect of reward context on working stable and flexible working memory performance and subjective feeling of effort. Results also showed no evidence for a relationship between the explore/exploit trade-off in foraging behavior and the flexibility/stability trade-off in working memory
Balancing the cognitive effort balance: effort being costly and valued
No full text2
Can exertion of cognitive effort be rewarding it itself? Where most research focuses on the
aversive side of effort, there are also situations in which people explicitly enjoy cognitive effort
exertion. Research on flow experiences points towards the intrinsic value of optimal
challenging activities, such that intermediately challenging tasks receive higher liking and
engagement scores compared to easy and difficult tasks. Intrinsic motivation accounts suggest
that this value could arise from its potential for improvement. Moreover, pupillary dynamics
have been associated with task engagement as well. The goal of this study was to investigate
when cognitive effort exertion is intrinsically rewarding and hence preferred, and which
cognitive processes are underlying this preference. In a design with individually defined
difficulty levels and subjective and objective measures of engagement, we showed that
intermediately challenging tasks received the highest subjective and objective engagement
scores, as well as the greatest prediction error magnitude. These findings indicate that
performance uncertainty might by the underlying mechanism of flow experiences. Moreover,
greater pupil sizes during cue period of intermediate tasks together with smaller pupil size
during easy and difficult tasks suggest that the brain at forehand differentiates between tasks
that are worthwhile it to engage in and tasks that are not. As the pupillary responses are
following noradrenaline-based arousal activity, locus-coeruleus activity might mediate this
relationship between optimal challenge preference and task uncertainty.
___________________________
Keywords: Cognitive effort; Cognitive avoidance; Flow; Motivation; Cognitive control;
Physiolog
The effect of HIV infection on frontostriatal inhibitory control in the era of combined antiretroviral therapy
No full textStudies on brain activity and connectivity in Human Immunodeficiency Virus (HIV) suggest that frontostriatal dysfunction plays a role in HIV-associated cognitive deficits. However, almost no research has been done to investigate frontostriatal functioning in a HIV population that is virally suppressed with combined antiretroviral therapy (cART). In this study, 27 HIV-positive participants, stable on cART and with an undetectable viral load, performed a stop signal anticipation task (SSAT) while being scanned with functional MRI (fMRI). This task activates the striatum during reactive inhibition (i.e. outright stopping of a response) and engages the frontostriatal network during proactive inhibition (i.e. anticipation of stopping). Results showed normal striatal activity in HIV+ participants during both reactive and proactive inhibition. During proactive inhibition, HIV+ participants showed less reaction time slowing during anticipation of a stop signal. This was paralleled in the brain by decreased dynamic activation in the right inferior frontal gyrus (IFG) with increased stop-signal probability, as well as decreased functional connectivity between the right striatum and the right IFG. These results suggest normal striatal functioning in a virally suppressed HIV population, but dysfunctional frontal activity and decreased frontostriatal connectivity. These findings serve as a stepping stone to research that distinguishes between the effects of HIV-infection and cART on frontostriatal functioning
The role of orexin in monetary and caloric reward anticipation and self-control: An fMRI study in narcolepsy patients
No full textIntroduction: Narcolepsy (NC) with cataplexy is a neurological sleeping disorder caused by an orexin deficiency. Besides sleep regulation, orexin signaling influences reward processing. As obesity is a common symptom in NC, we aimed to clarify the association between NC with a deficiency in orexin signaling and an increased BMI. Therefore we investigated the role of orexin in caloric- as well as monetary-related reward anticipation and self-control in patients with NC (n=27) compared with idiopathic hypersomnia (IH) (n=15) as well as healthy matched controls (HC) (n=21).
Methods: We used functional magnetic resonance imaging while participants performed a monetary- and caloric incentive delay task to measure the neural response towards high vs. low reward anticipation. Furthermore, we used a classic- and food Stroop task to measure the neuronal response towards incongruent vs. congruent and food words vs. neutral words.
Results and Interpretation: Our data indicates that NC patients do not suffer of a general cognitive control deficit, however they do suffer of alterations in the processing of food words. Our results showed increased ventral striatal activity during the processing of food words in NC- vs. IH patients and faster response times for NC patients vs. HC. These data provide a first indication that orexin may influence brain reward processing in a food specific way and this might explain the increased BMI over the course of the disease. However, the caloric incentive delay task did not support these effects, as there were no group differences for ventral striatal activity. Furthermore, we observed decreased activity in visual and motor preparatory brain regions within NC patients vs. HC (and IH patients) during the monetary- and caloric incentive delay tasks, which may reflect attentional and motivational dysfunction
The Effect of Mindful Eating Training on Midbrain and Striatal BOLD-responses to Reward Cues
No full textObesity has reached pandemic proportions, resulting in major negative consequences for people’s health. Obesity results from a positive energy balance between food intake and energy expenditure. A promising method to counteract the act of overeating is mindfulness training. In this randomized active-controlled experimental study it was investigated, for the first time, whether mindful eating training affects food-related neural reward mechanisms. More specifically, the study investigated whether mindful eating training decreases reward anticipation in striatal and midbrain reward regions either specifically to rewarding food cues or to reward cues in general. 61 Participants performed an incentive delay task with food and monetary trials during 3T fMRI scanning before and after 8 weeks of mindful eating or active-control training (educational cooking training). Results revealed decreased food-specific reward anticipation for midbrain but not striatum after mindful eating training. These results were not obtained for the active-control group, indicating a specific mindful eating training effect. The results suggest that mindful eating training decreases the rewarding value of food cues, which could result in decreased food-cue triggered overeating readily observed in the context of obesity
Neural mechanisms of action-selective and stimulus-selective stopping
No full textThe past decade has seen a surge of interest in selective stopping. Researchers studying
selective stopping have relied on the independent race model of simple stopping. Furthermore,
they have investigated selective stopping with a heterogeneous set of tasks, including
action-selective and stimulus-selective stop tasks. Action-selective stop tasks probe control
of specific actions and stimulus-selective stop tasks examine control triggered by specific
stimuli. However, it remains unclear whether the independent race model extends to selective
stopping and whether selective stopping is a homogeneous or heterogeneous construct.
Here, we addressed these important gaps.
We tested whether selective stopping performance is in agreement with predictions of the
independent race model, using a Bayesian hypothesis testing approach based on the Bayes
factor. We performed these tests at the group- and individual-level. We then compared
action- and stimulus-selective stopping in terms of performance and brain activation, using
functional magnetic resonance imaging.
We found violations of the predictions of the independent race model in 91% of the
individuals in action-selective stopping and 74% of the individuals in stimulus-selective stopping.
These individual violations were almost completely masked by the group performance.
Furthermore, performance did not differ between the two selective stopping types and there
appeared to be no differences in inhibition-related brain activity.
These results suggest that the independent race model does not generally extend to selective
stopping and that action-selective and stimulus-selective stopping form a homogeneous
construct
Balancing the cognitive effort balance: effort being costly and valued
No full textCan exertion of cognitive effort be rewarding it itself? Where most research focuses on the
aversive side of effort, there are also situations in which people explicitly enjoy cognitive effort
exertion. Research on flow experiences points towards the intrinsic value of optimal
challenging activities, such that intermediately challenging tasks receive higher liking and
engagement scores compared to easy and difficult tasks. Intrinsic motivation accounts suggest
that this value could arise from its potential for improvement. Moreover, pupillary dynamics
have been associated with task engagement as well. The goal of this study was to investigate
when cognitive effort exertion is intrinsically rewarding and hence preferred, and which
cognitive processes are underlying this preference. In a design with individually defined
difficulty levels and subjective and objective measures of engagement, we showed that
intermediately challenging tasks received the highest subjective and objective engagement
scores, as well as the greatest prediction error magnitude. These findings indicate that
performance uncertainty might by the underlying mechanism of flow experiences. Moreover,
greater pupil sizes during cue period of intermediate tasks together with smaller pupil size
during easy and difficult tasks suggest that the brain at forehand differentiates between tasks
that are worthwhile it to engage in and tasks that are not. As the pupillary responses are
following noradrenaline-based arousal activity, locus-coeruleus activity might mediate this
relationship between optimal challenge preference and task uncertainty.
___________________________
Keywords: Cognitive effort; Cognitive avoidance; Flow; Motivation; Cognitive control;
Physiolog
*Corresponding author
No full textAbstract: Accurate reconstruction of phylogenetic trees often involves solving hard optimisation problems, particularly the Maximum Parsimony (MP) and Maximum Likelihood (ML) problems. Various heuristics yield good results for these problems within reasonable time only on small datasets. This is a major impediment for large-scale phylogeny reconstruction. Roshan et al. introduced Rec-I-DCM3, an efficient and accurate meta-method for solving the MP problem on large datasets of up to 14,000 taxa. We improve the performance of Rec-I-DCM3 via parallelisation. The experiments demonstrate that our parallel method, PRec-I-DCM3, achieves significant improvements, both in speed and accuracy, over its sequential counterpart
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