Brains creating stories of selves: the neural basis of autobiographical reasoning.

in Social Cognitive and Affective Neuroscience (in press)

Personal identity critically depends on the creation of stories about the self and one's life. The present study investigates the neural substrates of autobiographical reasoning, a process central to the ... [more ▼]

Personal identity critically depends on the creation of stories about the self and one's life. The present study investigates the neural substrates of autobiographical reasoning, a process central to the construction of such narratives. During fMRI scanning, participants approached a set of personally significant memories in two different ways: on some trials, they remembered the concrete content of the events (autobiographical remembering), whereas on other trials they reflected on the broader meaning and implications of their memories (autobiographical reasoning). Relative to remembering, autobiographical reasoning recruited a left-lateralized network involved in conceptual processing (including the dorsal medial prefrontal cortex (MPFC), inferior frontal gyrus, middle temporal gyrus, and angular gyrus). The ventral MPFC-an area that may function to generate personal/affective meaning-was not consistently engaged during autobiographical reasoning across participants but, interestingly, the activity of this region was modulated by individual differences in interest and willingness to engage in self-reflection. These findings support the notion that autobiographical reasoning and the construction of personal narratives go beyond mere remembering in that they require deriving meaning and value from past experiences. [less ▲]

Exploration of the mechanisms underlying the ISPC effect: Evidence from behavioral and neuroimaging data

in Neuropsychologia (2013), 51

The item-specific proportion congruent (ISPC) effect in a Stroop task – the observation of reduced interference for color words mostly presented in an incongruent color – has attracted growing interest ... [more ▼]

The item-specific proportion congruent (ISPC) effect in a Stroop task – the observation of reduced interference for color words mostly presented in an incongruent color – has attracted growing interest since the original study by Jacoby (2003). Two mechanisms have been proposed to explain the effect: associative learning of contingencies and item-specific control through word reading modulation. Both interpretations have received empirical support from behavioral data. Therefore, the aim of this study was to investigate the responsible mechanisms of the ISPC effect with the classic two-item sets design using fMRI. Results showed that the ISPC effect is associated with increased activity in the anterior cingulate (ACC), dorsolateral prefrontal (DLPFC), and inferior and superior parietal cortex. Importantly, behavioral and fMRI analyses specifically addressing the respective contribution of associative learning and item-specific control mechanisms brought support for the contingency learning account of the ISPC effect. Results are discussed in reference to task and procedure characteristics that may influence the extent to which item-specific control and/or contingency learning contribute to the ISPC effect. [less ▲]

SNR dependence of mean kurtosis and how to correct it

in Proceedings of the International Society for Magnetic Resonance in Medicine ... Scientific Meeting and Exhibition. International Society For Magnetic Resonance in Medicine. Scientific Meeting and Exhibition (2013), 21

Etude IRM par tenseur de diffusion (DTI) des anomalies microstructurelles de la matière blanche dans la maladie de Parkinson

Poster (2012, March 21)

Introduction L’imagerie par résonance magnétique (IRM) conventionnelle du cerveau est réputée normale dans la maladie de Parkinson (MP), mais l’essor récent de techniques avancées offre de nouvelles ... [more ▼]

Introduction L’imagerie par résonance magnétique (IRM) conventionnelle du cerveau est réputée normale dans la maladie de Parkinson (MP), mais l’essor récent de techniques avancées offre de nouvelles perspectives, notamment l’IRM par tenseur de diffusion (DTI). Les études précédentes en la matière, hétérogènes dans leurs méthodes, montrent des résultats discordants. Ici, nous avons utilisé la DTI pour rechercher, sans hypothèse a priori, la présence d’anomalies microstructurelles au sein des principaux tracti de matière blanche dans la MP. Méthodes Soixante et un volumes en pondération de diffusion ont été acquis avec un système Allegra 3T (Siemens, Erlangen, Allemagne) au moyen d’une séquence DTI doublement refocalisée (1) chez 27 patients parkinsoniens non déments (durée moyenne d’évolution après le diagnostic : 5 ± 4.2 ans) et 25 contrôles d’âge (MP: 68,7±8,4; C: 65,1±8,8) et de genre similaires. Pour chaque sujet, les valeurs d’anisotropie fractionnelle (FA) et de diffusivité moyenne (MD) ont été extraites à partir d’un modèle du tenseur obtenu au moyen du logiciel ExploreDTI (2) faisant appel à la méthode RESTORE (3). Nous avons ensuite utilisé le module TBSS (v1.2) du logiciel FSL (4) pour conformer les images des scalaires dans un espace tridimensionnel commun puis rechercher, voxel-par-voxel, des différences entre les 2 groupes au sein du squelette de la matière blanche. Les résultats obtenus à l’issue d’un test par permutations (N=10000) ont été corrigés pour des comparaisons multiples. Résultats L’analyse des cartes de FA montre des valeurs significativement (P<0.05) plus élevées chez les patients dans plusieurs régions (5): fibres sous-corticales péri-rolandiques droites, parties du faisceau arqué droit, fibres du faisceau longitudinal inférieur et /ou fronto-occipital inférieur droit, fibres sous-corticales préfrontales gauches, partie postérieure du genou corps calleux. La comparaison inverse ne révèle aucun résultat significatif ni l’analyse des cartes de MD. Conclusions Ces résultats sont en accord avec les modèles physiopathologiques selon lesquels le primum movens dans la MP se situe dans une dysfonction synaptique et axonale (6,7). Une augmentation des valeurs de FA de la matière blanche dans la MP est en contradiction avec la plupart mais pas toutes (8,9) les études précédentes. L’hypothèse d’une diminution relative des fibres de croisement dans ces régions chez les patients mérite d’être testée au moyen de méthodes d’acquisition et d’analyse plus élaborées. Références 1. Nagy Z, et al. Magn Reson Med 2008; 60(5):1256-1260. 2. Leemans A, et al. Proc Intl Soc Mag Reson Med 17 2009;3537. (Abstract). 3. Chang LC, et al. Magn Reson Med 2005;3(5):1088-1095. 4. Smith SM et al. Neuroimage 2006; 31(4):1487-1505. 5. Catani M, et al. Cortex 2008; 44(8):1105-1132. 6. Schulz-Schaeffer WJ. Acta Neuropathol 2010; 120(2):131-143. 7. Cheng HC, et al. Ann Neurol 2010; 67(6):715-725. 8. Tessa C, et al. AJNR 2008; 29(4):674-680. 9. Wang JJ et al. Radiology 2011; 261(1):210-217. Remerciements Ce travail est financé par le Fonds de la Recherche Scientifique (FNRS-FRS) de la Communauté Française de Belgique. [less ▲]

Impact of noise correction on diffusion kurtosis estimation

in Proceedings of the International Society for Magnetic Resonance in Medicine ... Scientific Meeting and Exhibition. International Society For Magnetic Resonance in Medicine. Scientific Meeting and Exhibition (2012), 20

Influence of acute sleep loss on the neural correlates of alerting, orientating and executive attention components

in Journal of Sleep Research (2012), 21(6), 648-58

The fate of incoming stimuli during NREM sleep is determined by spindles and the phase of the slow oscillation

in Frontiers in Neurology (2012), 3(40), 1-11

The neural correlates of recollection and familiarity during aging

in Frontiers in Human Neuroscience (2012)

Modulation of brain activity during a Stroop inhibitory task by the kind of cognitive control required

in PLoS ONE (2012), 7(7), 41513

This study used a proportion congruency manipulation in the Stroop task in order to investigate, at the behavioral and brain substrate levels, the predictions derived from the Dual Mechanisms of Control ... [more ▼]

This study used a proportion congruency manipulation in the Stroop task in order to investigate, at the behavioral and brain substrate levels, the predictions derived from the Dual Mechanisms of Control (DMC) account of two distinct modes of cognitive control depending on the task context. Three experimental conditions were created that varied the proportion congruency: mostly incongruent (MI), mostly congruent (MC), and mostly neutral (MN) contexts. A reactive control strategy, which corresponds to transient interference resolution processes after conflict detection, was expected for the rare conflicting stimuli in the MC context, and a proactive strategy, characterized by a sustained task-relevant focus prior to the occurrence of conflict, was expected in the MI context. Results at the behavioral level supported the proactive/reactive distinction, with the replication of the classic proportion congruent effect (i.e., less interference and facilitation effects in the MI context). fMRI data only partially supported our predictions. Whereas reactive control for incongruent trials in the MC context engaged the expected fronto-parietal network including dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex, proactive control in the MI context was not associated with any sustained lateral prefrontal cortex activations, contrary to our hypothesis. Surprisingly, incongruent trials in the MI context elicited transient activation in common with incongruent trials in the MC context, especially in DLPFC, superior parietal lobe, and insula. This lack of sustained activity in MI is discussed in reference to the possible involvement of item-specific rather than list-wide mechanisms of control in the implementation of a high task-relevant focus. [less ▲]

Valuing One's Self: Medial Prefrontal Involvement in Epistemic and Emotive Investments in Self-views.

in Cerebral Cortex (2012), 22

Recent neuroimaging research has revealed that the medial prefrontal cortex (MPFC) is consistently engaged when people form mental representations of themselves. However, the precise function of this ... [more ▼]

Recent neuroimaging research has revealed that the medial prefrontal cortex (MPFC) is consistently engaged when people form mental representations of themselves. However, the precise function of this region in self-representation is not yet fully understood. Here, we investigate whether the MPFC contributes to epistemic and emotive investments in self-views, which are essential components of the self-concept that stabilize self-views and shape how one feels about oneself. Using functional magnetic resonance imaging, we show that the level of activity in the MPFC when people think about their personal traits (by judging trait adjectives for self-descriptiveness) depends on their investments in the particular self-view under consideration, as assessed by postscan rating scales. Furthermore, different forms of investments are associated with partly distinct medial prefrontal areas: a region of the dorsal MPFC is uniquely related to the degree of certainty with which a particular self-view is held (one's epistemic investment), whereas a region of the ventral MPFC responds specifically to the importance attached to this self-view (one's emotive investment). These findings provide new insight into the role of the MPFC in self-representation and suggest that the ventral MPFC confers degrees of value upon the particular conception of the self that people construct at a given moment. [less ▲]