Contribution of the subthalamic nucleus to motor, cognitive and limbic processes: an electrophysiological and stimulation study in monkeys

Deep brain stimulation of the subthalamic nucleus (STN) has become the gold standard surgical treatment for Parkinson’s disease and is being investigated for obsessive compulsive disorders. Even if the role of the STN in the behavior is well documented, its organization and especially its division into several functional territories is still debated. A better characterization of these territories and a better knowledge of the impact of stimulation would address this issue. We aimed to find specific electrophysiological markers of motor, cognitive and limbic functions within the STN and to specifically modulate these components. Two healthy non-human primates (Macaca fascicularis) performed a behavioral task allowing the assessment of motor, cognitive and limbic reward-related behavioral components. During the task, four contacts in the STN allowed recordings and stimulations, using low frequency stimulation (LFS) and high frequency stimulation (HFS). Specific electrophysiological functional markers were found in the STN with beta band activity for the motor component of behavior, theta band activity for the cognitive component, and, gamma and theta activity bands for the limbic component. For both monkeys, dorsolateral HFS and LFS of the STN significantly modulated motor performances, whereas only ventromedial HFS modulated cognitive performances. Our results validated the functional overlap of dorsal motor and ventral cognitive subthalamic territories, and, provide information that tends toward a diffuse limbic territory sensitive to the reward within the STN

Deltaic and Coastal Sediments as Recorders of Mediterranean Regional Climate and Human Impact Over the Past Three Millennia

International audienc

Midcingulate cortex contributions to behavioral regulation : studies of prefrontal dynamics and local perturbations

Les animaux ont la capacité fondamentale de structurer leurs actions en intégrant les issues de leurs choix afin de guider efficacement leurs recherches de récompenses. L'organisation cérébrale constitue le substrat de cette faculté de lier actes et récompenses dans le temps. Les activités des aires associatives, principalement préfrontales, reflètent des processus d'évaluation des récompenses et de contrôle de l'action. La recherche de dissociations fonctionnelles permet de révéler les contributions relatives des aires qui forment ce réseau. Nous avons comparé les activités de neurones du cortex préfrontal latéral (LPFC) avec celles du cortex cingulaire médian (MCC). Les activités du LPFC sont particulièrement fortes lors de la sélection d'une option suivant une instruction visuelle apprise. Les activités neuronales du MCC contiennent elles des représentations internes du suivi des récompenses et des stratégies à adopter en conséquence.Pour compléter l'étude corrélative des enregistrements unitaires, nous avons perturbé l'inhibition locale en injectant un antagoniste gabaergique dans le MCC. Ces interventions induisent des déficits à considérer l'historique des récompenses et des informations pour la régulation du comportement.Enfin, nous avons cherché dans les activités locales des déterminants intrinsèques à l'organisation du comportement. Nous avons extrait les signatures temporelles des activités du MCC et du LPFC que nous avons pu reproduire dans un modèle de réseau cortical par des jeux de conductances. Ces conductances fournissent un support mécanistique de la structuration des activités du réseau nécessaire à l'organisation temporelle des fonctions cognitivesAnimals have the fundamental ability to structure their actions by integrating the outcomes of their choices to effectively guide their search for future rewards. Brain organization forms the basis of this ability to link actions and rewards in time. The activities of associative areas, mainly prefrontal, reflect evaluation processes and control of action.The search for functional dissociation makes it possible to reveal the relative contributions of the areas which form this network. We compared the activities of neurons in the lateral prefrontal cortex (LPFC) with those of the median cingulate cortex (MCC) recorded in macaques. LPFC units are particularly recruited when selecting an option following a learned visual instruction. MCC neural activities contain internal representations of reward monitoring and strategies to be adopted accordingly.To complete the correlative study of unit recordings, we disrupted local inhibition by injecting a gabaergic antagonist into MCC. These disturbances induce deficits in behavioral regulation in light to the history of rewards and information.Finally, we looked in local activities for intrinsic determinants of the behavioral organization. We extracted the temporal signatures of MCC and LPFC activities and could reproduce them in a cortical network model by sets of conductances. These conductances provide a mechanistic support for the structuring of network activities necessary for the temporal organization of cognitive function

Contributions du cortex cingulaire médian à la régulation du comportement : études des dynamiques préfrontales et perturbations locales chez le primate

Animals have the fundamental ability to structure their actions by integrating the outcomes of their choices to effectively guide their search for future rewards. Brain organization forms the basis of this ability to link actions and rewards in time. The activities of associative areas, mainly prefrontal, reflect evaluation processes and control of action.The search for functional dissociation makes it possible to reveal the relative contributions of the areas which form this network. We compared the activities of neurons in the lateral prefrontal cortex (LPFC) with those of the median cingulate cortex (MCC) recorded in macaques. LPFC units are particularly recruited when selecting an option following a learned visual instruction. MCC neural activities contain internal representations of reward monitoring and strategies to be adopted accordingly.To complete the correlative study of unit recordings, we disrupted local inhibition by injecting a gabaergic antagonist into MCC. These disturbances induce deficits in behavioral regulation in light to the history of rewards and information.Finally, we looked in local activities for intrinsic determinants of the behavioral organization. We extracted the temporal signatures of MCC and LPFC activities and could reproduce them in a cortical network model by sets of conductances. These conductances provide a mechanistic support for the structuring of network activities necessary for the temporal organization of cognitive functionsLes animaux ont la capacité fondamentale de structurer leurs actions en intégrant les issues de leurs choix afin de guider efficacement leurs recherches de récompenses. L'organisation cérébrale constitue le substrat de cette faculté de lier actes et récompenses dans le temps. Les activités des aires associatives, principalement préfrontales, reflètent des processus d'évaluation des récompenses et de contrôle de l'action. La recherche de dissociations fonctionnelles permet de révéler les contributions relatives des aires qui forment ce réseau. Nous avons comparé les activités de neurones du cortex préfrontal latéral (LPFC) avec celles du cortex cingulaire médian (MCC). Les activités du LPFC sont particulièrement fortes lors de la sélection d'une option suivant une instruction visuelle apprise. Les activités neuronales du MCC contiennent elles des représentations internes du suivi des récompenses et des stratégies à adopter en conséquence.Pour compléter l'étude corrélative des enregistrements unitaires, nous avons perturbé l'inhibition locale en injectant un antagoniste gabaergique dans le MCC. Ces interventions induisent des déficits à considérer l'historique des récompenses et des informations pour la régulation du comportement.Enfin, nous avons cherché dans les activités locales des déterminants intrinsèques à l'organisation du comportement. Nous avons extrait les signatures temporelles des activités du MCC et du LPFC que nous avons pu reproduire dans un modèle de réseau cortical par des jeux de conductances. Ces conductances fournissent un support mécanistique de la structuration des activités du réseau nécessaire à l'organisation temporelle des fonctions cognitive

Specific frontal neural dynamics contribute to decisions to check

International audienceCuriosity and information seeking potently shapes our behaviour and are thought to rely on the frontal cortex. Yet, the frontal regions and neural dynamics that control the drive to check for information remain unknown. Here we trained monkeys in a task where they had the opportunity to gain information about the potential delivery of a large bonus reward or continue with a default instructed decision task. Single-unit recordings in behaving monkeys reveal that decisions to check for additional information first engage midcingulate cortex and then lateral prefrontal cortex. The opposite is true for instructed decisions. Importantly, deciding to check engages neurons also involved in performance monitoring. Further, specific midcingulate activity could be discerned several trials before the monkeys actually choose to check the environment. Our data show that deciding to seek information on the current state of the environment is characterized by specific dynamics of neural activity within the prefrontal cortex

Local inhibitory control of frontal network metastabilityunderlies the temporal signature of cognitive states

Cortical neural dynamics organizes over multiple anatomical and temporal scales. The mechanistic origin of the temporal organization and its contribution to cognition remain unknown. Here we demonstrate that a temporal signature (autocorrelogram time constant and latency) of neural activity enlightens this organization. In monkey frontal areas, recorded during flexible cognitive decisions, temporal signatures display highly specific area-dependent ranges, as well as anatomical and cell-type distributions. Moreover, temporal signatures are functionally adapted to behaviorally relevant timescales. Fine-grained biophysical network models, constrained to account for temporal signatures, reveal that after-hyperpolarization potassium and inhibitory GABA-B conductances critically determine areas' specificity. They mechanistically account for temporal signatures by organizing activity into metastable states, with inhibition controlling state stability and transitions. As predicted by models, state durations non-linearly scale with temporal signatures in monkey, matching behavioral timescales. Thus, local inhibitory-controlled metastability constitutes the dynamical core specifying the temporal organization of cognitive functions in frontal areas

New core-top Mg/Ca calibration of multiple benthic foraminiferal species: Thermometry of the thermocline water in tropical western Atlantic

International audienc

Correlations of the rectus abdominis muscle anatomy with anthropometric measurements

International audienc