Karim N'Diaye

Centre National de la Recherche Scientifique / French National Centre for Scientific Research, Institut du Cerveau / Paris Brain Institute (ICM) UMR 7225, Faculty Member

Sorbonne University, Institut du Cerveau et de la Moelle épinière (ICM), Post-Doc

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Papers by Karim N'Diaye

I can’t get it off my mind: Attentional bias in former and current cocaine addiction

Journal of Psychopharmacology

Background: Cocaine addiction is a global health issue with limited therapeutic options and a hig... more Background: Cocaine addiction is a global health issue with limited therapeutic options and a high relapse rate. Attentional bias towards substance-related cues may be an important factor for relapse. However, it has never been compared in former and current cocaine-dependent patients. Methods: Attentional bias towards cocaine-related words was assessed using an emotional Stroop task in cocaine-dependent patients ( N = 40), long-term abstinent former cocaine-dependent patients ( N = 24; mean abstinence: 2 years) and control subjects ( N = 28). Participants had to name the colour of cocaine-related words, neutral words and colour names. We assessed response times using an automatic voice-onset detection method we developed and we measured attentional bias as the difference in response times between cocaine-related and neutral conditions. Results: There was an overall group effect on attentional bias towards cocaine, but no group effect on the colour Stroop effect. Two-by-two comparis...

Dynamique et topographie des réseaux neuronaux corticaux impliqués dans la perception du temps

L'objectif de ce travail a ete d'explorer les bases neurales de la perception du temps ch... more L'objectif de ce travail a ete d'explorer les bases neurales de la perception du temps chez l'humain en analysant les correlats electromagnetiques du jugement temporel par reconstruction des generateurs corticaux du signal de scalp electroencephalographique et magnetoencephalographique. Dans deux articles experimentaux, nous montrons qu’independamment de la modalite sensorielle, un reseau etendu d'aires corticales est implique dans la discrimination de durees circaseconde et que le decours temporel de l'activite au sein de ce reseau s'accorde mal avec le mecanisme de pacemaker-accumulateur du modele de temps scalaire. Nous proposons donc dans un article theorique, co-ecrit avec Warren Meck, de montrer en quoi le modele Striatal Beat Frequency offre un cadre biologiquement plus realiste permettant de rapprocher les mecanismes a l'oeuvre dans la memoire de travail et dans le traitement temporel.

Joint contributions of metacognition and self-beliefs to uncertainty-guided checking behavior

Scientific Reports

Checking behavior is a natural and adaptive strategy for resolving uncertainty in everyday situat... more Checking behavior is a natural and adaptive strategy for resolving uncertainty in everyday situations. Here, we aimed at investigating the psychological drivers of checking and its regulation by uncertainty, in non-clinical participants and controlled experimental settings. We found that the sensitivity of participants’ explicit confidence judgments to actual performance (explicit metacognition) predicted the extent to which their checking strategy was regulated by uncertainty. Yet, a more implicit measure of metacognition (derived from asking participants to opt between trials) did not contribute to the regulation of checking behavior. Meanwhile, how participants scaled on questionnaires eliciting self-beliefs such as self-confidence and self-reported obsessive–compulsive symptoms also predicted participants’ uncertainty-guided checking tendencies. Altogether, these findings demonstrate that checking behavior is likely the outcome of a core explicit metacognitive process operating ...

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A cross-species assessment of behavioral flexibility in compulsive disorders

Communications Biology

Lack of behavioral flexibility has been proposed as one underlying cause of compulsions, defined ... more Lack of behavioral flexibility has been proposed as one underlying cause of compulsions, defined as repetitive behaviors performed through rigid rituals. However, experimental evidence has proven inconsistent across human and animal models of compulsive-like behavior. In the present study, applying a similarly-designed reversal learning task in two different species, which share a common symptom of compulsivity (human OCD patients and Sapap3 KO mice), we found no consistent link between compulsive behaviors and lack of behavioral flexibility. However, we showed that a distinct subgroup of compulsive individuals of both species exhibit a behavioral flexibility deficit in reversal learning. This deficit was not due to perseverative, rigid behaviors as commonly hypothesized, but rather due to an increase in response lability. These cross-species results highlight the necessity to consider the heterogeneity of cognitive deficits in compulsive disorders and call for reconsidering the rol...

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Joint contribution of metacognition and self-beliefs to uncertainty-guided checking behavior

Checking behavior is a natural and adaptive strategy in uncertain situations. Here, we aimed at i... more Checking behavior is a natural and adaptive strategy in uncertain situations. Here, we aimed at investigating the psychological drivers of checking and its regulation by uncertainty, in non-clinical participants and controlled experimental settings. We found that the sensitivity of participants’ explicit confidence judgments to actual performance (explicit metacognition) predicted the extent to which their checking strategy was regulated by uncertainty. This was, however, not the case of how participants used confidence to guide subsequent decision-making (implicit metacognition). Meanwhile, how participants scaled on questionnaires eliciting self-beliefs such as self-confidence and self-reported obsessive-compulsive symptoms also predicted participants’ uncertainty-guided checking tendencies. Altogether, these findings demonstrate that checking is likely the outcome of a core metacognitive process operating at the scale of single decisions, while remaining influenced by general sel...

A cross-species assessment of behavioral flexibility in compulsive disorders

ABSTRACTBackgroundCompulsive behaviors, one of the core symptoms of Obsessive-Compulsive Disorder... more ABSTRACTBackgroundCompulsive behaviors, one of the core symptoms of Obsessive-Compulsive Disorder (OCD), are defined as repetitive behaviors performed through rigid rituals. The lack of behavioral flexibility has been as being one of the primary causes of compulsions, but studies exploring this dimension have shown inconsistencies in different tasks performed in human and animal models of compulsive behavior. The aim of this study was so to assess the involvement of behavioral flexibility in compulsion, with a similar approach across different species sharing a common symptom of compulsivity.Methods40 OCD patients, 40 healthy individually matched control subjects, 26 C57BL/6J Sapap3 KO mice and 26 matched wildtype littermates were included in this study. A similar reversal learning task was designed to assess behavioral flexibility in parallel in these two species.ResultsWhen considered as homogeneous groups, OCD patients and KO mice expressing compulsive behaviors did not significa...

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Alpha band activity and CNV reflect the evaluation of target probability

Metacognitive monitoring in severe resistant obsessive-compulsive disorder treated by deep-brain stimulation

Metacognition is the high-level psychological processes that enable to monitor and control one’s ... more Metacognition is the high-level psychological processes that enable to monitor and control one’s own cognitive functioning, e.g. the confidence one has in a perceptual decision. Despite “pathological doubt” being a core feature of obsessive-compulsive disorder and repetitive checking, a common OCD symptom, being conceivable as an ill-founded attempt to accumulate evidence to restore confidence in one’s decisions, little is known on metacognition in OCD and how these processes may evolve through therapeutical interventions. In the present study, we explored metacognitive monitoring of perceptual decisions in severe resistant OCD patients, both in terms of quantitative behavioral markers, and in terms of their neural bases. We capitalized on a clinical trial assessing the efficacy of high-frequency deep brain stimulation of the subthalamic nucleus and the striatum to longitudinally assess patients on their metacognitive monitoring performance as they went through a cross-over design w...

Connectivité fonctionnelle des réseaux cortico-striataux chez des patients atteints de trouble obsessionnel compulsif de vérification : étude du « resting state » en IRM fonctionnelle

European Psychiatry, 2014

Ce que la pleine conscience fait au cerveau

European Psychiatry, 2014

A la recherche du temps perçu

Le selfie clinique: l'avènement de la smart auto-évaluation?

Induction of a hypomanic state by stimulation of the limbic territory of the subtbalamic nucleus

Neural correlates of different self-conscious emotions identified by functional magnetic resonance imaging

Connectivité fonctionnelle des réseaux cortico-striataux chez des patients atteints de trouble obsessionnel compulsif de vérification: étude du «resting state» en IRM fonctionnelle

Le trouble obsessionnel compulsif (TOC) est une pathologie fréquente, touchant 2 à 3 % de la popu... more Le trouble obsessionnel compulsif (TOC) est une pathologie fréquente, touchant 2 à 3 % de la population [1].L’implication de structures cortico-striato-thalamiques dans la symptomatologie du TOC est consensuellement reconnue [2]. Parmi elles, le cortex orbitofrontal (OFC), le cortex cingulaire antérieur (ACC) et le striatum ventral sont des structures d’un intérêt particulier dans les mécanismes de prises de décision associés au TOC.La mesure de la connectivité fonctionnelle basée sur l’IRM fonctionnelle (IRMf) permet d’étudier les liens fonctionnels entre plusieurs régions cérébrales [3]. Les études précédentes fournissant des résultats contradictoires sur la connectivité fonctionnelle dans le TOC entre le striatum ventral, l’OFC et le ACC [4], nous étudions la connectivité fonctionnelle basée sur l’IRMf chez 12 patients atteints de TOC de vérification (YBOCS &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 16) contrastés avec 11 témoins enregistrés en « état de repos » (resting state) avec une séquence EPI sur une IRM 3 T (CENIR, Institut du Cerveau et de la Moelle épinière, Paris). Notre analyse utilise l’OFC, le ACC et le striatum ventral comme régions d’intérêt (ROI), à partir de coordonnées définies dans une étude en IRMf précédemment menée dans notre laboratoire. Nous avons étudié la différence de connectivité entre ces régions deux à deux (ROI-to-ROI analysis) et entre ces régions et le reste du cortex (seed-voxel analysis).Nous souhaitons également étudier la corrélation entre la connectivité entre ces régions et la sévérité du TOC, mesurée avec l’échelle YBOCS.Nos données sont en cours d’analyse, mais des résultats préliminaires montrent une hypoconnectivité entre le striatum ventral droit et l’ACC chez les patients (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0,05). Ces résultats préliminaires nous orientent vers une poursuite de l’étude de la connectivité fonctionnelle dans le TOC, et notamment l’analyse de l’influence de différents paramètres cliniques (début des troubles, durée de la maladie, sous-type de TOC) sur cet aspect de la physiopathologie.

Contingent negative/magnetic variation during time perception: Simultaneous MEG and EEG recordings

Parsing the temporal evolution of brain activity in duration discrimination with electro-and magneto-encephalography

Thermal imaging of facial expressions: investigating thermal correlates of Facial Action Units activities

Thermography for emotions study, why? FLIR SC3000 * Non invasive technique * Avoids overloading e... more

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The neural bases of checking behavior: An fMRI study in OCD patients

L'Encéphale, 2012

Les bases neurales du comportement de vérification : une étude en IRMf chez des patients souffrant de trouble obsessionnel compulsif (TOC)

L'Encéphale, 2012

Karim N'Diaye

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