83 research outputs found
Lateral prefrontal model-based signatures are reduced in healthy individuals with high trait impulsivity
High impulsivity is an important risk factor for addiction with evidence from
endophenotype studies. In addiction, behavioral control is shifted toward the
habitual end. Habitual control can be described by retrospective updating of
reward expectations in ‘model-free’ temporal-difference algorithms. Goal-
directed control relies on the prospective consideration of actions and their
outcomes, which can be captured by forward-planning ‘model-based’ algorithms.
So far, no studies have examined behavioral and neural signatures of model-
free and model-based control in healthy high-impulsive individuals. Fifty
healthy participants were drawn from the upper and lower ends of 452
individuals, completing the Barratt Impulsiveness Scale. All participants
performed a sequential decision-making task during functional magnetic
resonance imaging (fMRI) and underwent structural MRI. Behavioral and fMRI
data were analyzed by means of computational algorithms reflecting model-free
and model-based control. Both groups did not differ regarding the balance of
model-free and model-based control, but high-impulsive individuals showed a
subtle but significant accentuation of model-free control alone. Right lateral
prefrontal model-based signatures were reduced in high-impulsive individuals.
Effects of smoking, drinking, general cognition or gray matter density did not
account for the findings. Irrespectively of impulsivity, gray matter density
in the left dorsolateral prefrontal cortex was positively associated with
model-based control. The present study supports the idea that high levels of
impulsivity are accompanied by behavioral and neural signatures in favor of
model-free behavioral control. Behavioral results in healthy high-impulsive
individuals were qualitatively different to findings in patients with the same
task. The predictive relevance of these results remains an important target
for future longitudinal studies
The Neural Basis of Decision-Making and Reward Processing in Adults with Euthymic Bipolar Disorder or Attention-Deficit/Hyperactivity Disorder (ADHD)
Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder (BD) share DSM-IV criteria in adults and cause problems in decision-making. Nevertheless, no previous report has assessed a decision-making task that includes the examination of the neural correlates of reward and gambling in adults with ADHD and those with BD
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SOX2 is an amplified lineage-survival oncogene in lung and esophageal squamous cell carcinomas
Lineage survival oncogenes are activated by somatic DNA alterations in cancers arising from the cell lineages in which these genes play a role in normal development.1,2 Here we show that a peak of genomic amplification on chromosome 3q26.33, found in squamous cell carcinomas (SCCs) of the lung and esophagus, contains the transcription factor gene SOX2—which is mutated in hereditary human esophageal malformations3 and necessary for normal esophageal squamous development4, promotes differentiation and proliferation of basal tracheal cells5 and co-operates in induction of pluripotent stem cells.6,7,8 SOX2 expression is required for proliferation and anchorage-independent growth of lung and esophageal cell lines, as shown by RNA interference experiments. Furthermore, ectopic expression of SOX2 cooperated with FOXE1 or FGFR2 to transform immortalized tracheobronchial epithelial cells. SOX2-driven tumors show expression of markers of both squamous differentiation and pluripotency. These observations identify SOX2 as a novel lineage survival oncogene in lung and esophageal SCC
Het nemen van beslissingen door volwassenen met ADHD:Een systematisch literatuuronderzoek
Personen met aandachtstekortstoornis met hyperactiviteit (ADHD) hebben een grotere kans om minder goede (levens)beslissingen te nemen en om risicovolle activiteiten te ondernemen dan personen zonder ADHD. Mogelijk komt dit doordat de kenmerken van ADHD van invloed zijn op het besluitvormingsproces. Hoewel beslissingsproblematiek reeds uitgebreid is onderzocht bij kinderen en adolescenten met ADHD, is er nog relatief weinig bekend over de besluitvorming van volwassenen met ADHD. Om die reden was het doel van dit literatuuronderzoek de aard en omvang van eventuele tekorten in het besluitvormingsproces van volwassenen met ADHD vast te stellen. Hiertoe is de bestaande literatuur, waarin de prestatie van volwassenen met ADHD op beslissingstaken werd vergeleken met de prestatie van een gezonde controlegroep, systematisch doorzocht, waartoe de databases PsycINFO, MEDLINE en PubMed zijn geraadpleegd. In totaal werden er 31 studies geïncludeerd. In de meerderheid van de studies (i.e. 55 %) weken de prestaties van volwassenen met ADHD af op een of meer van de gebruikte beslissingstaken in vergelijking met de controlegroep(en). Dit literatuuronderzoek levert daarmee voorzichtig bewijs voor het bestaan van verschillen in het besluitvormingsproces tussen gezonde individuen en volwassenen met ADHD. De grote inconsistentie in de bevindingen wordt deels verklaard door de verscheidenheid aan domeinen van besluitvorming die werden onderzocht, de comorbide stoornissen van de participanten en het medicatiegebruik in de ADHD-groepen. Het literatuuronderzoek besluit met een bespreking van de implicaties die de bevindingen hebben voor theorieën over de onderliggende mechanismen van ADHD
Risk factors for addiction and their association with model-based behavioral control
Addiction shows familial aggregation and previous endophenotype research suggests that healthy relatives of addicted individuals share altered behavioral and cognitive characteristics with individuals suffering from addiction. In this study we asked whether impairments in behavioral control proposed for addiction, namely a shift from goal-directed, model-based toward habitual, model-free control, extends toward an unaffected sample (n = 20) of adult children of alcohol-dependent fathers as compared to a sample without any personal or family history of alcohol addiction (n = 17). Using a sequential decision-making task designed to investigate model-free and model-based control combined with a computational modeling analysis, we did not find any evidence for altered behavioral control in individuals with a positive family history of alcohol addiction. Independent of family history of alcohol dependence, we however observed that the interaction of two different risk factors of addiction, namely impulsivity and cognitive capacities, predicts the balance of model-free and model-based behavioral control. Post-hoc tests showed a positive association of model-based behavior with cognitive capacity in the lower, but not in the higher impulsive group of the original sample. In an independent sample of particularly high- vs. low-impulsive individuals, we confirmed the interaction effect of cognitive capacities and high vs. low impulsivity on model-based control. In the confirmation sample, a positive association of omega with cognitive capacity was observed in highly impulsive individuals, but not in low impulsive individuals. Due to the moderate sample size of the study, further investigation of the association of risk factors for addiction with model-based behavior in larger sample sizes is warranted
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