Biology subjects

Roiser, J.

Publications and source records attributed to Roiser, J..

7 recordsLinked to original sources

bioRxiv2024

Depression in Parkinson's disease is associated with dopamine unresponsive reduced reward sensitivity during effort-based decision making

Willingness to exert effort for a given goal is dependent on the magnitude of the potential rewards and effort costs of an action. Such effort-based decision making is an essential component of motivation, in which the dopaminergic system plays a key role. Depression in Parkinsons disease (PD) is common, disabling and has poor outcomes. Motivational symptoms such as apathy and anhedonia, are prominent in PD depression and related to dopaminergic loss. We hypothesised that dopamine-dependent disruption in effort-based decision-making contributes to depression in PD. In the present study, an effort-based decision-making task was administered to 62 patients with PD, with and without depression, ON and OFF their dopaminergic medication across two sessions, as well as to 34 patients with depression and 29 matched controls on a single occasion. During the task, on each trial, participants decided whether to accept or reject offers of different levels of monetary reward in return for exerting varying levels of physical effort via grip force, measured using individually calibrated dynamometers. The primary outcome variable was choice (accept/decline offer), analysed using both logistic mixed-effects modelling and a computational model which dissected the individual contributions of reward and effort on depression and dopamine state in PD. We found PD depression was characterised by lower acceptance of offers, driven by markedly lower incentivisation by reward (reward sensitivity), compared to all other groups. Within-subjects analysis of the effect of dopamine medication revealed that, although dopamine treatment improves reward sensitivity in non-depressed PD patients, this therapeutic effect is not present in PD patients with depression. These findings suggest that disrupted effort-based decision-making, unresponsive to dopamine, contributes to PD depression. This highlights reward sensitivity as a key mechanism and treatment target for PD depression that potentially requires non-dopaminergic therapies.

neuroscience↗

bioRxiv2023

Approach-avoidance reinforcement learning as a computational and translational model of anxiety-related avoidance

Although avoidance is a prevalent feature of anxiety-related psychopathology, differences in the measurement of avoidance between humans and non-human animals hinder our progress in its theoretical understanding and treatment. To address this, we developed a novel translational measure of anxiety-related avoidance in the form of an approach-avoidance reinforcement learning task, by adapting a paradigm from the non-human animal literature to study the same cognitive processes in human participants. We used computational modelling to probe the putative cognitive mechanisms underlying approach-avoidance behaviour in this task and investigated how they relate to subjective task-induced anxiety. In a large online study (n = 372), participants who experienced greater task-induced anxiety avoided choices associated with punishment, even when this resulted in lower overall reward. Computational modelling revealed that this effect was explained by greater individual sensitivities to punishment relative to rewards. We replicated these findings in an independent sample (n = 627) and we also found fair-to-excellent reliability of measures of task performance in a sub-sample retested one week later (n = 57). Our findings demonstrate the potential of approach-avoidance reinforcement learning tasks as translational and computational models of anxiety-related avoidance. Future studies should assess the predictive validity of this approach in clinical samples and experimental manipulations of anxiety.

neuroscience↗

bioRxiv2021

A Hierarchical Reinforcement Learning Model Explains Individual Differences in Attentional Set Shifting

Attentional set shifting refers to the ease with which the focus of attention is directed and switched. Cognitive tasks such as CANTAB IED reveal great variation in set shifting ability in the general population, with notable impairments in those with psychiatric diagnoses. The attentional and learning processes underlying this cognitive ability, and how they lead to the observed variation remain unknown. To directly test this, we used a modelling approach on two independent large-scale online general-population samples performing CANTAB IED and psychiatric symptom assessment. We found a hierarchical model that learnt both feature values and dimension attention best explained the data, and that compulsive symptoms were associated with slower learning and higher attentional bias to the first relevant stimulus dimension. This data showcase a new methodology to analyse data from the CANTAB IED task, and suggest a possible mechanistic explanation for the variation in set shifting performance, and its relationship to compulsive symptoms.

neuroscience↗

bioRxiv2020

Subjective Beliefs In, Out, and About Control: A Quantitative Analysis

A critical facet of adjusting one’s behaviour after succeeding or failing at a task is assigning responsibility for the ultimate outcome. Humans have trait- and state-like tendencies to implicate aspects of their own behaviour (called ‘internal’ ascriptions) or facets of the particular task or Lady Luck (‘chance’). However, how these tendencies interact with actual performance is unclear. We designed a novel task in which subjects had to learn the likelihood of achieving their goals, and the extent to which this depended on their efforts. High internality (Levenson I-score) was associated with decision making patterns that are less vulnerable to failure, and at the same time less oriented to more rewarding achievements. Our computational analyses suggested that this depended heavily on the adjustment in the perceived achievability of riskier goals following failure. We found beliefs about chance not to be explanatory of choice behaviour in our task. Beliefs about powerful others were strong predictors of behaviour, but only when subjects lacked substantial influence over the outcome. Our results provide an evidentiary basis for heuristics and learning differences that underlie the formation and maintenance of control expectations by the self.Competing Interest StatementThe authors have declared no competing interest.View Full Text

animal behavior and cognition↗

bioRxiv2020

A Comparison of Pruning During Multi-Step Planning in Depressed and Healthy Individuals

BackgroundReal-life decisions are often complex because they involve making sequential choices that constrain future options. We have previously shown that to render such multi-step decisions manageable, people "prune" (i.e. selectively disregard) branches of decision trees that contain negative outcomes. We have theorized that sub-optimal pruning contributes to depression by promoting an oversampling of branches that result in unsavoury outcomes, which results in a negatively-biased valuation of the world. However, no study has tested this theory in depressed individuals. MethodsThirty unmedicated depressed and 31 healthy participants were administered a sequential reinforcement-based decision-making task to determine pruning behaviours, and completed measures of depression and anxiety. Computational, Bayesian and frequentist analyses examined group differences in task performance and relationships between pruning and depressive symptoms. ResultsConsistent with prior findings, participants robustly pruned branches of decision trees that began with large losses, regardless of the potential utility of those branches. However, there was no group difference in pruning behaviours. Further, there was no relationship between pruning and levels of depression/anxiety. LimitationsThe relatively small sample size limited the examination of individual differences. The use of other heuristics that are used to render complex decisions feasible, such as memoization and fragmentation, were not examined. ConclusionsWe found no evidence that sub-optimal pruning is evident in depression. Future research could determine whether maladaptive pruning behaviours are observable in specific sub-groups of depressed patients (e.g. in treatment-resistant individuals), or whether misuse of other heuristics may contribute to depression.

systems biology↗

bioRxiv2019

Risk taking to obtain reward: gender differences and associations with emotional and depressive symptoms in a nationally representative cohort of UK adolescents.

BackgroundLarge population-based studies of neuropsychological factors that characterize or precede depressive symptoms are rare and we know little about gender differences in these associations.\n\nMethodsThe Millennium Cohort is a representative UK birth cohort of children born between 2000 and 2002. The Cambridge Gambling Task (CGT) was completed at ages 11 (n=12,355) and 14 (n=10,578). Our main exposure was proportion of points gambled, when odds of winning were above chance (risk taking to obtain reward). We also examined how much adolescents adjusted bets as odds of winning increased (risk adjustment). Outcomes were emotional symptoms at age 11 (SDQ) and depressive symptoms at age 14 (sMFQ). We calculated cross-sectional associations, and a longitudinal association from age 11 to 14, using linear regressions before and after adjusting for confounders.\n\nResultsFemales were less risk taking than males (e.g. females bet 9.22, 95% CI 8.65 to 9.80, percentage points lower at age 11). In univariable models there were cross-sectional associations between risk taking and emotional (age 11) or depressive (age 14) symptoms (e.g. at age 14, a 20-percentage point increase in risk taking was associated with a 0.52 reduction in sMFQ points, 95% CI -.71 to -.33). However, cross-sectional associations were explained by gender differences (at age 14 the association adjusted for gender was: .05, 95% CI -.15 to .25). Longitudinally, there was weak evidence of an association between risk taking and depressive symptoms in females only (a 20-point increase in risk taking at age 11 was associated with a reduction of 0.31 sMFQ points at age 14 (95% CI -.60 to -.02).\n\nConclusionsWe found evidence that adolescent females were less likely to take risks than adolescent males. There was no strong evidence of an association between risk taking and emotional and depressive symptoms, after accounting for gender.\n\nAbbreviationsCGT: Millennium Cohort Study (MCS); Cambridge Gambling Task (CGT); Strengths and Difficulties Questionnaire (SDQ); sMFQ: short Mood and Feelings Questionnaire.

epidemiology↗

bioRxiv2018

Short-term fasting selectively influences impulsivity in healthy individuals

Previous research has shown that short-term fasting in healthy individuals (HIs) is associated with changes in risky decision-making. The current experiment was designed to examine the influence of short-term fasting in HIs on four types of impulsivity: reflection impulsivity, risky decision-making, delay aversion, and action inhibition. HIs were tested twice, once when fasted for 20 hours, and once when satiated. Participants demonstrated impaired action inhibition when fasted; committing significantly more errors of commission during a food-related Affective Shifting Task. Participants also displayed decreased reflection impulsivity when fasted, opening significantly more boxes during the Information Sampling Task (IST). There were no significant differences in performance between fasted and satiated sessions for risky decision-making or delay aversion. These findings may have implications for understanding eating disorders such as Bulimia Nervosa (BN). Although BN has been characterised as a disorder of poor impulse control, inconsistent findings when comparing individuals with BN and HIs on behavioural measures of impulsivity question this characterisation. Since individuals with BN undergo periods of short-term fasting, the inconsistent findings could be due to differences in the levels of satiation of participants. The current results indicate that fasting can selectively influence performance on the IST, a measure of impulsivity previously studied in BN. However, the results from the IST were contrary to the original hypothesis and should be replicated before specific conclusions can be made.

neuroscience↗