Biology subjects

Quednow, B. B.

Publications and source records attributed to Quednow, B. B..

9 recordsLinked to original sources

bioRxiv2026

A computational neuroimaging account of impulsive premature decision-making

Impulsivity is a multidimensional construct with distinct implications for the pathophysiology and treatment of various neuropsychiatric conditions, including substance use disorders, behavioural addictions, attention deficit hyperactivity disorder, psychosis, and personality disorders. One proposed behavioural subtype, premature responding impulsivity (PRI), appears to be influenced by neuromodulatory pathways frequently implicated in these disorders, in particular dopamine neurotransmission, known for its role in contingency learning. Still, the neurobiological basis of PRI in humans remains insufficiently understood. Here, we theorize that PRI reflects the brains capacity to adapt to environmental uncertainty. To test this hypothesis, twenty-four healthy adults (mean age 22.6 years; 12 females) completed a novel decision-making task featuring alternating stable and volatile probabilistic cue contingencies while undergoing functional magnetic resonance imaging (fMRI). A hierarchical Bayesian model estimated PRI as an urgency-to-respond process, whose parameters were dynamically modulated by volatility. These model-derived indices correlated with established trait impulsivity measures, supporting their construct validity. Model-based fMRI analyses identified a distributed cortico-subcortical network including anterior insula, dorsal anterior cingulate cortex, striatum, and monoaminergic midbrain regions, whose activity tracked within-trial PRI estimates as they evolved over time. Connectivity analyses further showed that high volatility enhanced interactions between subnetworks typically associated with promoting or inhibiting impulsive action. Together, these results outline a neurocomputational account in which environmental uncertainty modulates PRI through interacting brain circuits, offering a principled framework for further probing the transdiagnostic role of impulsivity across neuropsychiatric and neuropsychopharmacological contexts.

neuroscience↗

bioRxiv2025

Increased cocaine self-administration and prefrontal cortical dysregulation of glutamatergic and GABAergic signaling in a rat model for sensory processing sensitivity

While all organisms are tuned to the environment, some are more sensitive than others. In humans, this is reflected by the trait sensory processing sensitivity (SPS), comprising 20-30% of the population, which is characterized by heightened emotional reactivity, deeper information processing, greater awareness of their environment, and susceptibility to overstimulation. It is expected but unproven that high SPS increases the risk for psychostimulant use. To clarify this, we selected Wistar rats on behavioral extremes related to SPS and subjected them to isolation, neutral, and enriched housing conditions, followed by cocaine self-administration (S/A). Subsequently, we investigated neurobiological differences in excitatory/inhibitory neurotransmission of the low- and high SPS-like rats by evaluating key glutamatergic and GABAergic proteins in the infralimbic (ILc) and prelimbic (PLc) subregions of the prefrontal cortex. High SPS-like rats displayed higher cocaine intake during 1h S/A training sessions in isolated versus social conditions, whereas low SPS-like rats showed similar intake across housing conditions. During 6h S/A sessions, high SPS-like rats displayed a higher cocaine intake regardless of housing and greater motivation for cocaine under a progressive ratio scheme. High SPS-like cocaine-naive rats exhibited lower expression of glutamatergic and GABAergic markers in ILc and PLc compared to low SPS-like cocaine-naive rats. The opposite occurred after cocaine exposure: low and high SPS-like rats showed lower and higher expression levels, respectively, compared to naive counterparts. In conclusion, these findings suggest that a high SPS-like trait with associated glutamatergic and GABAergic alterations might be a risk factor for the development of cocaine use disorder.

neuroscience↗

bioRxiv2025

Differential alterations in peripheral tryptophan pathways in methamphetamine versus MDMA users are linked to their contrasting psychiatric symptoms

Methamphetamine (METH, "Crystal Meth") and 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") are two types of substituted amphetamines that share structural-chemical similarities but exhibit contrasting acute and chronic effects including addictive liability. Tryptophan (TRY) pathways are involved in pleiotropic physiological functions at the interface of brain-body connections. Preclinical evidence suggests that amphetamines may modulate these pathways and, thus, indirectly influence brain functions via persistent alterations of peripheral metabolites. However, little is known about alterations of TRY-related metabolites in the blood and their clinical implications in chronic users of MDMA and METH. Hence, we characterized serum levels of TRY-related metabolites in a comparative cross-sectional study including n=36 chronic MDMA users, n=33 chronic METH users, and n=71 sex-matched, stimulant-naive healthy controls (Ntotal=140). An ultra- high performance liquid chromatography-mass spectrometry method was used to determine TRY metabolites. Combining metabolite levels, metabolic ratios, and network analysis we found robust evidence of divergent pathway alterations between METH and MDMA users. Chronic METH use was particularly associated with a depletion of serum TRY and serotonin levels, and a general activation of kynurenine pathways, while chronic MDMA use was linked to a selective activation of the OH-kynurenine metabolic branch. Metabolite changes were associated with the severity of psychopathology in the depression and psychosis domains across groups. Altogether, our findings demonstrate differential changes of serum TRY pathways in chronic MDMA and METH users. Persistent alterations of these pathways might contribute to the contrasting clinical profile of the substances and constitute a peripheral dimension of neurochemical plasticity with relevant implications for therapeutic targets.

biochemistry↗

bioRxiv2025

Adolescent Peer Victimization Through a Trauma Lens: Heightened Startle Response, Increased Pupil Dilation, Elevated Cortisol, and Reduced Heart Rate Variability in Young Adulthood

BACKGROUNDAdolescent peer victimization (PV) is a prevalent social stressor associated with potential long-term psychological and physiological consequences. Yet, the mechanisms underlying enduring alterations in stress-regulatory systems remain underexplored. This multimodal study examines autonomic, endocrine, and affective reactivity in young adults with a history of severe PV. METHODSEyeblink startle electromyograms, pupil dilation, hair cortisol, resting heart rate variability, and self-reported state anxiety were assessed in 182 young adults (age 22) with longitudinal data on adolescent PV (ages 11-20). Effects were estimated using a counterfactual framework with genetically informed inverse probability weighting--leveraging polygenic risk scores and genetic ancestry--and adjustment for time-varying confounders. RESULTSVictims exhibited heightened startle amplitudes compared to controls, with negative stimuli (angry faces) further exaggerating amplitude and prolonging latency. Pupil dilation increased in response to negative stimuli, but was otherwise blunted. Victims also showed reduced resting heart rate variability, elevated hair cortisol, and slower state anxiety recovery across the session. Depression moderated several effects; more depressed victims showed hypocortisolism and reduced autonomic reactivity. CONCLUSIONSFindings provide converging evidence and mechanistic insight into potential links between PV and trauma-like physiological effects, suggesting sustained alterations into young adulthood. Targeted interventions are needed to reduce PV and its stress-related dysregulation, preventing potential long-term psychiatric and societal sequelae.

physiology↗

bioRxiv2024

Decoding of resting-state using task-based multivariate pattern analysis supports the Incentive-Sensitization Theory in nicotine use disorder

BackgroundThe Incentive-Sensitization Theory postulates that addiction is primarily driven by the sensitization of the brains reward system to addictive substances, such as nicotine. According to this theory, exposure to such substances leads to an increase in wanting, while liking the experience remains relatively unchanged. Although this candidate mechanism has been well substantiated through animal brain research, its translational validity for humans has only been partially demonstrated so far, with evidence from human neuroscience data being very limited. MethodsFrom fMRI data of N=31 individuals with Nicotine Use Disorder, we created multivoxel patterns capable of capturing wanting and liking-related dimensions from a smoking cue-reactivity task. Using these patterns, we then designed a novel resting-state reading method to evaluate how much wanting or liking still persist as a neural trace after watching the cues. ResultsWe found that the persistence of wanting-related brain patterns at rest increases with longer smoking history but this was not the case for liking-related patterns. Interestingly, such behavior has not been observed for non-temporal measures of smoking intensity. ConclusionThis study provides basic human neuroscience evidence that the dissociation between liking and wanting escalates over time, further substantiating the Incentive-Sensitization Theory, at least for Nicotine Use Disorder. These results suggest that treatment approaches could be personalized to account for the variability in individuals neural adaptation to addiction by considering how individuals differ in the extent to which their incentive salience system is sensitized.

neuroscience↗

bioRxiv2023

Plasma endocannabinoids in cocaine dependence and their interaction with cocaine craving and metabotropic glutamate receptor 5 density in the human brain

Animal models indicate that the endocannabinoid system (ECS) plays a modulatory role in stress and reward processing, both crucially impaired in addictive disorders. Preclinical findings showed endocannabinoid-modulated synaptic plasticity in reward brain networks linked to the metabotropic-glutamate-5 receptor (mGluR5), contributing to drug-reinforcing effects and drug-seeking behavior. Although animal models postulate a link between ECS and cocaine addiction, human translational studies are lacking. Here, we tested previous preclinical findings by investigating plasma endocannabinoids (eCBs) anandamide (AEA), 2-arachidonoylglycerol (2-AG), and the related N-acylethanolamines (NAEs) palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), including their interaction with cerebral mGluR5, in chronic cocaine users (CU). We compared basal plasma concentrations between chronic CU (N=103; 69 recreational CU and 34 dependent CU) and stimulant-naive healthy controls (N=92). Follow-up basal eCB/NAE plasma levels after 12 months were used for reliability and stability check (CU: N=33; controls: N=43). In an additional analysis using 11C-ABP688 positron emission tomography (PET) in a male subsample (CU: N=18; controls: N=16), we investigated the relationships between eCBs/NAEs and mGluR5 density in the brain. We found higher 2-AG plasma levels in dependent CU compared to controls and recreational CU. 2-AG levels were stable over time across all groups. In the PET-subsample, a positive association between 2-AG and mGluR5 brain density only in CU was found. Our results corroborate animal findings suggesting an alteration of the ECS in cocaine dependence and an association between peripheral 2-AG levels and cerebral mGluR5 in humans. Therefore, the ECS might be a promising pharmaco-therapeutic target for novel treatments of cocaine dependence.

neuroscience↗

bioRxiv2022

Thalamic volume and functional connectivity are associated with nicotine dependence severity and craving

Tobacco smoking is associated with deleterious health outcomes. Most smokers want to quit smoking, yet relapse rates are high. Understanding neural differences associated with tobacco use may help generate novel treatment options. Several animal studies have recently highlighted the central role of the thalamus in substance use disorders, but this research focus has been understudied in human smokers. Here, we investigated associations between structural and functional magnetic resonance imaging measures of the thalamus and its subnuclei to distinct smoking characteristics. We acquired anatomical scans of 32 smokers as well as functional resting-state scans before and after a cue-reactivity task. Thalamic functional connectivity was associated with craving and dependence severity, whereas the volume of the thalamus was associated with dependence severity only. Craving, which fluctuates rapidly, was best characterized by differences in brain function, whereas the rather persistent syndrome of dependence severity was associated with both brain structural differences and function. Our study supports the notion that functional versus structural measures tend to be associated with behavioral measures that evolve at faster versus slower temporal scales, respectively. It confirms the importance of the thalamus to understand mechanisms of addiction and highlights it as a potential target for brain-based interventions to support smoking cessation, such as brain stimulation and neurofeedback.

neuroscience↗

bioRxiv2021

Enhanced negative response to stress following morphine administration increases wanting of social reward

Animal research suggests a central role of the -opioid receptor (MOR) system in regulating affiliative behaviors and in mediating the stress-buffering function of social contact. However, the neurochemistry of stress-related social contact seeking in humans is still poorly understood. In a randomized, double-blind, between-subject design, healthy female volunteers (N = 80) received either 10 mg of the -opioid agonist morphine sulfate, or a placebo. Following a standardized psychosocial stress induction, participants engaged in a social reward task, in which the motivation to obtain skin-to-skin social touch and the hedonic reactions elicited by such touch were assessed. Morphine prevented the increase of salivary cortisol typically observed following acute stress exposure. Notably, this altered HPA axis responsivity was associated with increased negative affect in response to psychosocial stress, and with enhanced subjective wanting of highly rewarding social contact. These findings provide novel evidence on the effect of exogenous opioids administration on the reactions to psychosocial stress and point to a state-dependent regulation of social motivation.

neuroscience↗

bioRxiv2018

Self-regulation of the Dopaminergic Reward Circuit in Cocaine Users with Mental Imagery and Neurofeedback

Background: Enhanced drug-related reward sensitivity accompanied by impaired sensitivity to non-drug related rewards in the mesolimbic dopamine system are thought to underlie the broad motivational deficits and dysfunctional decision-making frequently observed in cocaine use disorder (CUD). Effective approaches to modify this imbalance and reinstate non-drug reward responsiveness are urgently needed. Here we examine whether cocaine users (CU) can use mental imagery of non-drug rewards to self-regulate the ventral tegmental area and substantia nigra (VTA/SN). We expected that compulsive and obsessive thoughts about cocaine consumption would hamper the ability to self-regulate the VTA/SN. Finally, we tested if self-regulation of the VTA/SN can be improved with real-time fMRI (rtfMRI) neurofeedback (NFB).\n\nMethods: Twenty-two CU and 28 healthy controls (HC) were asked to voluntarily up-regulate VTA/SN activity with rewarding non-drug imagery alone, or combined with rtfMRI NFB of VTA/SN activity. Obsessive-compulsive drug use was measured with the Obsessive Compulsive Cocaine Use Scale (OCCUS).\n\nResults: CU were able to induce activity in the dopaminergic midbrain and other reward regions with reward imagery. The ability to self-regulate the VTA/SN was reduced in those with more severe obsessive-compulsive drug use. NFB enhanced the effect of non-drug imagery.\n\nConclusion: CU can voluntary activate their reward system through non-drug related imagery and improve this ability with rtfMRI NFB. Combining reward imagery and rtFMRI NFB has great potential for modifying the maladapted reward sensitivity and reinstating non-drug reward responsiveness. This motivates further work to examine the therapeutic potential of cognitive neurostimulation in CUD.

neuroscience↗