Séminaires des laboratoires

Salle des Voûtes, Campus St Charles - 11H - 13003 Marseille
Christian Lorenzi,
CNRS & Ecole normale supérieure, Paris,

Processing time with our auditory system

Debate on how speech information is represented in the auditory system has revolved around the role of two neural/perceptual features encoding the temporal modulations of the acoustic signal (the “temporal envelope”, ENV, and “temporal fine structure”, TFS), their relative contribution to intelligibility and how that might be degraded by lesions to the peripheral and central auditory system. We will review psychophysical studies that investigated the development of ENV/TFS perception, the effects of cochlear and central lesions, and the relationship between ENV/TFS perception and speech intelligibility. Our results suggest that: i) the processing of ENV and TFS is “functional” by 6 months, and fine-tuned by language exposure between 6 and 10 months, ii) ENV is more important for speech identification, whereas TFS is more important for the segregation of competing sound sources, iii) reduced ability to process ENV and/or TFS explains deficits typically associated with cochlear and central damage and ageing.

*References: *
Shamma, S., & Lorenzi, C. (2013). On the balance of envelope and temporal fine structure in the encoding of speech in the early auditory system. /Journal of the Acoustical Society of America, 133, /2818-2833/./
Lorenzi, C., Debruille, L., Garnier, S., Fleuriot, P., & Moore, B.C.J. (2009). Abnormal auditory temporal processing for frequencies where absolute thresholds are normal. /Journal of the Acoustical Society of America, 125, 27-30./
Lorenzi, C., Gilbert, G., Carn, H., Garnier, S., & Moore, B.C.J. (2006). Speech perception problems of the hearing impaired reflect inability to use temporal fine structure. /Proceedings of the National Academy of Science/ /USA/, /103(49)/, 18866-18869.
 

à définir
Grégoire Borst

Laboratoire de psychologie et du développement de l'enfant UMR8240
Université Sorbonne
Paris

Rôle du contrôle cognitif dans le développement cognitif et les apprentissages scolaires de l'enfant et de l'adolescent

Certains modèles du développement cognitif de l’enfant et de l'adolescent considèrent que la capacité à contrôler ses pensées, ses actions, ses stratégies et son impulsivité (contrôle cognitif et contrôle de soi) constitue un des mécanismes clefs du développement cognitif et scolaire de l'enfant d'âge pré-scolaire et d'âge scolaire et de l'adolescent. Nous présenterons les résultats d'un ensemble d'études dans différentes domaines cognitifs (nombre, catégorisation, raisonnement, prise de perspective, créativité) et différentes situations scolaires (résolution de problèmes arithmétiques, comparaison de nombres décimaux, comparaison de lettre) combinant des approches expérimentales et de neuroimagerie qui suggèrent que le contrôle cognitif pourrait être un mécanisme clef du développement dans ces différents domaines cognitifs et scolaires. Dans une deuxième partie du séminaire, nous présenterons les résultats d'un ensemble d'études en IRM anatomique, chez l'enfant et l'adulte, qui suggèrent que la variabilité interindividuelle observée dans différents fonctions cognitives (contrôle cognitif, lecture et cognition numérique) est en partie liée à des contraintes cérébrales précoces, déterminées in utero et stables au cours du développement (i.e., motifs sulco-gyraux).

LPC, salle CH57, Campus St Charles - 13003 Marseille
Rani Moran
University College London | UCL · Wellcome Trust Centre for Neuroimaging

Retrospective Model-Based Inference Guides Model-Free Credit Assignment

To adapt to their environments, organisms need to learn which actions are rewarding in different states of the world. Extensive research in Reinforcement Learning (RL) has shown that organisms cope efficiently with this credit-assignment problem, even when their actions are executed under challenging conditions of action and/or state uncertainty. However, little is known about such credit-assignment even for the common case where this uncertainty is subsequently resolved. Such is the case, for example, when you ask for a salary-raise without knowing whether your employer is in a good or a bad mood and a few days later you learn that she was in a bad mood when she approved your request. Does this knowledge modulate your credit assignment? Here, I will examine this question from the perspective of the interaction between habitual (model-free; MF) and goal-directed (model-based; MB) systems. Whereas previous research in RL has mostly focused on an MB prospective-planning function, I will present a novel theory of MB retrospective-inference and an experimental test of this theory based on a novel bandit task. According to our theory, an MB system resolves the uncertainty that prevailed when actions were taken and hence guides MF credit-assignment. In support of our theory, we found that when subject’s momentary uncertainty about which bandit had generated an outcome was resolved by subsequent information, they assigned most of the credit to the bandit they inferred to have been responsible. I will discuss how these findings enrich our knowledge on the variety of MB functions and the scope of MB-MF interactions.

à 13:30

à 13:30

Emmanuel Barbeau
Centre de Recherche Cerveau et Cognition, UMR5549, Toulouse, France

Familiarity and recollection: revisiting dogmas

We recognize everyday dozens of objects and faces. Actually this ability is so efficient that we do not even pay any attention to it. However, it has been shown that we can rapidly store thousands of new pictures and sometimes for a very long time without rehearsal in the meantime. Phenomenologically two processes are supposed to participate to recognition memory, one fast and acontextual called familiarity, the other slower and associated with the context in which the stimulus was encountered called recollection. Although there is agreement on the core network of brain regions involved in recollection, surprisingly little is known about familiarity, quite probably because the psychological and physiological signals associated with familiarity are fast, but also much weaker, than those associated with recollection. In fact, it is not even clear if familiarity is a single process as often presented. In this talk, I will review recent studies in which we used a combination of new paradigms, neuropsychological and intracerebral electrophysiological studies to identify the network of brain regions involved in familiarity.

Séminaire Corentin Gonthier

11 heures - LPC, Salle des Voûtes, Campus St Charles - 13003 Marseille

Corentin Gonthier
MCF en psychologie différentielle et statistiques
LPE - CRPCC Université Rennes 2

Un contrôle cognitif sans fonctions exécutives : la variabilité selon le modèle à deux mécanismes de contrôle (DMC)

L'aptitude des individus à réguler leur comportement est souvent étudiée sous l'angle des fonctions exécutives : des fonctions élémentaires comme l'inhibition ou la flexibilité. Mais une autre approche consiste à définir le contrôle cognitif comme une aptitude relativement unitaire, ce qui ouvre la voie à des recherches portant sur la façon dont ce contrôle est mis en place. Le modèle à deux mécanismes de contrôle (DMC : Braver et al., 2007) propose par exemple que le contrôle cognitif peut se faire de façon proactive ou de façon réactive.
Je présenterai cette approche originale du contrôle cognitif et une série de travaux portant sur la mesure des mécanismes de contrôle proactif et réactif, la possibilité d'induire les participants à utiliser l'un des deux mécanismes, et leur lien avec la capacité en mémoire de travail.