Biology subjects

Robbins, T.

Publications and source records attributed to Robbins, T..

12 recordsLinked to original sources

bioRxiv2026

Neurobehavioural correlates of changing one's mind in ADHD and OCD

Cognitive flexibility is an executive function that allows individuals to adjust behaviour in response to changing environmental demands. We assessed volitional switching under uncertainty, without rule-based learning, in the Change Your Mind task. Nineteen patients with obsessive-compulsive disorder (OCD), 19 patients with attention-deficit hyperactivity disorder (ADHD) and matched control participants (20 per group) completed the task whilst undergoing a functional MRI scan. The task was a two-alternative forced choice paradigm where each stimulus was presented twice successively, with spurious feedback following the first presentation. This allowed participants the opportunity to repeat or change their response. Participants with ADHD changed their response more frequently than controls following a previously correct response, associated with reduced accuracy on the second trial. This was accompanied with smaller differences between change and repeat trials in the superior frontal gyrus, paracingulate gyrus and frontal pole compared to controls. Participants with OCD did not differ from healthy controls in their performance but exhibited greater activity on both change and repeat trials in the pre- and postcentral gyri than controls. These results point to distinct neurobehavioural differences in patients with ADHD and OCD underlying what is often termed more broadly inflexible behaviour.

neuroscience↗

bioRxiv2024

Mesencephalic projections to the nucleus accumbens shell modulate value updating during probabilistic reversal learning

Cognitive flexibility, the capacity to adapt behaviour to changes in the environment, is impaired in a range of brain disorders, including substance use disorder and Parkinsons disease. Putative neural substrates of cognitive flexibility include mesencephalic pathways to the ventral striatum (VS) and dorsomedial striatum (DMS), hypothesised to encode learning signals needed to maximize rewarded outcomes during decision-making. However, it is unclear whether mesencephalic projections to the ventral and dorsal striatum are distinct in their contribution to flexible reward-related learning. Here, rats acquired a two-choice spatial probabilistic reversal learning (PRL) task, reinforced on an 80%:20% basis, that assessed the flexibility of behaviour to repeated reversals of response-outcome contingencies. We report that optogenetic stimulation of projections from the ventral tegmental area (VTA) to the nucleus accumbens shell (NAcbS) in the VS significantly impaired reversal learning when optical stimulation was temporally aligned with negative feedback (i.e., reward omission). Moreover, the exploitation-exploration parameter, {beta}, was increased (indicating greater exploitation of information) when this pathway was optogenetically stimulated after a spurious loss (i.e. an incorrect (20%) response at the 80% reinforrced location) compared to after a spurious win (i.e. a correct (20%) response at the 20% reinforced location). VTA [->] NAcbS stimulation during other phases of the behavioural task was without effect. Optogenetic stimulation of projection neurons from the substantia nigra (SN) to the DMS, aligned either with reward receipt or omission or prior to making a choice, had no effect on reversal learning. These findings are consistent with the notion that enhanced activity in VTA [->] NAcbS projections leads to maladaptive perseveration as a consequence of an inappropriate bias to exploitation via positive reinforcement.

animal behavior and cognition↗

bioRxiv2023

Oxytocin, but not vasopressin, decreases willingness to harm others by promoting moral emotions of guilt and shame

Prosocial and moral behaviors have overlapping neural systems but whether they involve similar neurochemical systems is unclear. In the current pre-registered randomized placebo controlled trial on 180 adult male and female subjects we investigated effects of intranasal administration of two prosocial neuropeptides, oxytocin or vasopressin, on moral emotion ratings for situations involving accidental or intentional harm to others and in judgments of moral dilemmas where harm is inflicted for a greater good. Oxytocin, but not vasopressin, enhanced feelings of guilt and shame only for intentional harm and reduced endorsement of choices where direct intentional harm to others could achieve a greater good. Effects of oxytocin on guilt and shame were partially mediated by trait empathy. Overall, findings demonstrate for the first time that oxytocin, but not vasopressin, promotes unwillingness to deliberately harm others irrespective of the consequences. This may reflect stronger associations between oxytocin and empathy and vasopressin with aggression.

neuroscience↗

bioRxiv2023

5-HT 2A and 5-HT 2C receptor antagonism differentially modulates reinforcement learning and cognitive flexibility: behavioral and computational evidence

Cognitive flexibility, the ability to adapt behavior in response to a changing environment, is disrupted in several neuropsychiatric disorders, including obsessive-compulsive disorder (OCD) and major depressive disorder (MDD). Evidence suggests that flexibility, which can be operationalized using reversal learning tasks, is modulated by serotonergic transmission. However, how exactly flexible behavior and associated reinforcement learning (RL) processes are modulated by 5-HT action on specific receptors is unknown. We investigated the effects of 5-HT2A receptor (5-HT2AR) and 5-HT2C receptor (5-HT2CR) antagonism on cognitive flexibility and underlying RL mechanisms. Thirty-six male Lister hooded rats were trained on a touchscreen visual discrimination and reversal task. We evaluated the effects of systemic treatments with the 5-HT2AR and 5-HT2CR antagonists M100907 and SB-242084, respectively, on reversal learning performance and performance on probe trials where correct and incorrect stimuli were presented with a third, probabilistically rewarded, stimulus. Computational models were fitted to task choice data to extract RL parameters, including a novel model designed specifically for this task. 5-HT2AR antagonism impaired reversal learning during certain phases. 5-HT2CR antagonism, on the other hand, impaired learning from positive feedback. RL models further differentiated these effects. 5-HT2AR antagonism decreased punishment learning rate at high and low doses. The low dose also increased exploration (beta) and increased stimulus and side stickiness (kappa). 5-HT2CR antagonism also increased beta, but reduced side stickiness. These data indicate that 5-HT2A and 5-HT2CRs both modulate different aspects of flexibility, with 5-HT2ARs modulating learning from negative feedback and 5-HT2cRs for learning from positive feedback.

animal behavior and cognition↗

bioRxiv2023

Computational modeling of reinforcement learning and functional neuroimaging of probabilistic reversal dissociates compulsive behaviors in Gambling and Cocaine Use Disorders

Cognitive flexibility refers to the ability to adjust to changes in the environment and is essential for adaptive behavior. It can be investigated using laboratory tests such as probabilistic reversal learning (PRL). In individuals with both Cocaine Use Disorder (CUD) and Gambling Disorder (GD), overall impairments in PRL flexibility are observed. However, it is poorly understood whether this impairment depends on the same brain mechanisms in cocaine and gambling addictions. Reinforcement learning (RL) is the process by which rewarding or punishing feedback from the environment is used to adjust behavior, to maximise reward and minimise punishment. Using RL models, a deeper mechanistic explanation of the latent processes underlying cognitive flexibility can be gained. Here, we report results from a re-analysis of PRL data from control participants (n=18) and individuals with either GD (n=18) or CUD (n=20) using a hierarchical Bayesian RL approach. We observed significantly reduced stimulus stickiness (i.e., stimulus-bound perseveration) in GD, which may reflect increased exploratory behavior that is insensitive to outcomes. RL parameters were unaffected in CUD. We relate the behavioral findings to their underlying neural substrates through an analysis of task-based fMRI data. We report differences in tracking reward and punishment expected values (EV) in individuals with GD compared to controls, with greater activity during reward EV tracking in the cingulate gyrus and amygdala. In CUD, we observed reduced responses to positive punishment prediction errors (PPE) and increased activity following negative PPEs in the superior frontal gyrus compared to controls. Thus, an RL framework serves to differentiate behavior in a probabilistic learning paradigm in two compulsive disorders, GD and CUD.

neuroscience↗

bioRxiv2022

Neurobehavioral precursors of compulsive cocaine-seeking in dual fronto-striatal circuits

Only some individuals using drugs recreationally eventually become addicted, and persist in drug seeking and taking despite adverse consequences. The neurobehavioral determinants of this individual vulnerability have not been fully elucidated. We report that in drug naive rats the future tendency to develop compulsive cocaine seeking is characterised by behavioral stickiness-related functional hypoconnectivity between the prefrontal cortex and posterior dorsomedial striatum in combination with impulsivity-related structural alterations in the infralimbic cortex, anterior insula and nucleus accumbens. These findings show that the vulnerability to develop compulsive cocaine seeking behavior stems from pre-existing structural or functional changes in two distinct cortico-striatal systems that underlie deficits in impulse control and goal-directed behavior.

neuroscience↗

bioRxiv2022

Blocking D2/D3 dopamine receptors increases volatility of beliefs when we learn to trust others

The ability to flexibly adjust beliefs about other people is crucial for human social functioning. Dopamine has been proposed to regulate the precision of beliefs, but direct behavioural evidence of this is lacking. We investigated how a relatively high dose of the selective D2/D3 dopamine receptor antagonist sulpiride impacts learning about other peoples prosocial attitudes in a repeated trust game. Using a Bayesian model of belief updating, we show that sulpiride increased the volatility of beliefs, which led to higher precision-weights on prediction errors. This effect was entirely driven by participants with genetically conferring higher dopamine availability (Taq1a polymorphism). Higher precision weights were reflected in higher reciprocal behaviour in the repeated trust game but not in single-round trust games. This finding suggests that antipsychotic medication might acutely reduce rigidity of pathological beliefs.

neuroscience↗

bioRxiv2022

A hierarchical genotyping framework using DNA melting temperatures applied to adenovirus species typing

Known genetic variation for a pathogen, in conjunction with post-PCR melting curve analysis, can be leveraged to provide increased taxonomic detail for pathogen identification in commercial molecular diagnostic tests. The increased taxonomic detail may be used by clinicians and public health decision makers to observe circulation patterns, monitor for outbreaks, and inform local testing practices. We propose a method for expanding the taxonomic resolution of PCR diagnostic systems by incorporating a priori knowledge of the assay design and publicly available sequence information into a genotyping classification model. For multiplexed PCR systems, this framework is generalized to incorporate information from multiple assays that react with different gene targets of the same pathogen to increase classification accuracy. To illustrate the method, a hierarchical classification model is developed for the BioFire(R) Respiratory 2.1 Panel and the BioFire(R) Respiratory 2 Panel (collectively the BioFire Respiratory Panels - highly multiplexed PCR diagnostic tests) to predict the species of human adenovirus (HAdV) from Adenovirus Detected test results. Performance of the classification model was characterized via a 10-fold cross-validation on a labeled dataset and exhibited 95% {+/-} 4% accuracy. The model was then applied to the BioFire(R) Syndromic Trends dataset, which contains deidentified patient test data from BioFire Respiratory Panels collected at over 100 sites across the globe since 2015. Adenovirus Detected test results in BioFire Syndromic Trends were classified to produce predicted prevalence of each HAdV species within the United States from 2018 through 2021. These results show a marked change in both the predicted prevalence for HAdV and the species makeup with the onset of the COVID-19 pandemic. In particular, HAdV-B decreased from a pre-pandemic predicted prevalence of up to 40% to less than 5% in 2021, while HAdV-A and HAdV-F species both increased in predicted prevalence. Author SummaryIn the diagnosis of infectious disease there is often a trade-off between time to result, cost, and the amount of information gained about the pathogen. We develop a method that can provide increased genotypic information about a pathogen in a test result, with no additional time or cost. Our method is applied to the BioFire Respiratory(R) 2.1 Panel and the BioFire Respiratory(R) 2 Panel to speciate positive test results for adenovirus. The method shows robust performance in correctly identifying the adenovirus species from the test results. We estimate the prevalence of each adenovirus species in the United States by applying this method to adenovirus positive test results in the BioFire Syndromic Trends network. This information can be used in near real-time to augment the Centers for Disease Control and Prevention efforts to monitor adenovirus species circulation. Our mathematical framework can be generalized to other genotyping applications.

molecular biology↗

bioRxiv2021

A novel analytical decoder of BOLD signals for dissociating latent neurobehavioral processes

How to retrieve latent neurobehavioral processes from complex neurobiological signals is an important yet unresolved challenge. Here, we develop a novel approach, orthogonal-Decoding multi-Cognitive Processes (DeCoP), to reveal underlying latent neurobehavioral processing and show that its performance is superior to traditional non-orthogonal decoding in terms of both false inference and robustness. Processing value and salience information are two fundamental but mutually confounded pathways of reward reinforcement essential for decision making. During reward/punishment anticipation, we applied DeCoP to decode brain-wide responses into spatially overlapping, yet functionally independent, evaluation and readiness processes, which are modulated differentially by meso-limbic vs nigro-striatal dopamine systems. Using DeCoP, we further demonstrated that most brain regions only encoded abstract information but not the exact input, except for dACC and insula. Furthermore, our novel analytical principle could be applied generally to decode multiple latent neurobehavioral processes and thus advance both the design and hypothesis testing for cognitive tasks.

neuroscience↗

bioRxiv2021

Brain Laterality Dynamics Support Human Cognition

Hemispheric lateralization constitutes a core architectural principle of human brain organization underlying cognition, often argued to represent a stable, trait-like feature. However, emerging evidence underlines the inherently dynamic nature of brain networks, in which time-resolved alterations in functional lateralization remain uncharted. Integrating dynamic network approaches with the concept of hemispheric laterality, we map the spatiotemporal architecture of whole-brain lateralization in a large sample of high-quality resting-state fMRI data (N=991, Human Connectome Project). We reveal distinct laterality dynamics across lower-order sensorimotor systems and higher-order associative networks. Specifically, we expose two aspects of the laterality dynamics: laterality fluctuations, defined as the standard deviation of laterality time series, and laterality reversal, referring to the number of zero-crossings in laterality time series. These two measures are associated with moderate and extreme changes in laterality over time, respectively. While laterality fluctuations depict positive association with language function and cognitive flexibility, laterality reversal shows a negative association with the same neurocognitive factors. These opposing interactions indicate a dynamic balance between intra- and inter-hemispheric communication, i.e., segregation and integration of information across hemispheres. Furthermore, in their time-resolved laterality index, the default-mode and language networks correlate negatively with visual/sensorimotor and attention networks, indicating flexible while parallel processing capabilities that are linked to better out-of-scanner cognitive performance. Finally, the laterality dynamics correlate with regional metabolism and structural connectivity and showed significant heritability. Our results provide insights into the adaptive nature of the lateralized brain and new perspectives for future studies of human cognition, genetics and brain disorders.

neuroscience↗

bioRxiv2021

Opposing roles of the dorsolateral and dorsomedial striatum in the acquisition of skilled action sequencing

The shift in control from dorsomedial to dorsolateral striatum during skill and habit formation has been well established, but whether striatal subregions orchestrate this shift co-operatively or competitively remains unclear. Cortical inputs have also been implicated in the shift towards automaticity, but it is unknown if they mirror their downstream striatal targets across this transition. We addressed these questions using a five-step heterogeneous action sequencing task in rats that is optimally performed by automated chains of actions. By optimising automatic habitual responding, we discovered that loss of function in the dorsomedial striatum accelerated sequence acquisition. In contrast, loss of function in the dorsolateral striatum impeded acquisition of sequencing, demonstrating functional opposition within the striatum. Unexpectedly the medial prefrontal cortex was not involved, however the lateral orbitofrontal cortex was critical. These results shift current theories about striatal control of behavior to a model of competitive opposition, where the dorsomedial striatum acts in a gating role to inhibit dorsolateral-striatum driven behavior.

neuroscience↗

bioRxiv2017

The Control of Tonic Pain by Active Relief Learning

Tonic pain after injury characterises a behavioural state that prioritises recovery. Although generally suppressing cognition and attention, tonic pain needs to allow effective relief learning so that the cause of the pain can be reduced if possible. Here, we describe a central learning circuit that supports learning of relief and concurrently suppresses the level of ongoing pain. We used computational modelling of behavioural, physiological and neuroimaging data in two experiments in which subjects learned to terminate tonic pain in static and dynamic escape-learning paradigms. In both studies, we show that active relief-seeking involves a reinforcement learning process manifest by error signals observed in the dorsal putamen. Critically, this system also uses an uncertainty ( associability) signal detected in pregenual anterior cingulate cortex that both controls the relief learning rate, and endogenously and parametrically modulates the level of tonic pain. The results define a self-organising learning circuit that allows reduction of ongoing pain when learning about potential relief.

neuroscience↗