Neural basis of recognition memory within the medial temporal lobe

Wiedererkennungsgedächtnis ist die Fähigkeit, zu beurteilen, ob ein Objekt bereits aufgetreten und bekannt ist. Einiger Konsens besteht darüber, dass der mediale Temporallappen (MTL) zur Erinnerung notwendig ist, und vieles weist auf den Hippocampus als Hauptsubstrat hin. Dennoch bleibt das neuronale Netzwerk, welches das Wiedererkennungsgedächtnis unterstützt, hoch umstritten. Um den Einfluss des MTL auf die Wiedererkennung zu untersuchen, haben wir eine Geruchsbasierte Wiedererkennungsgedächtnisaufgabe durch Nager mit Fluoreszenz in situ Hybridisierung der unmittelbaren frühen Gen-pre-mRNA $\it Arc$ (Aktivität reguliert Zytoskelett) kombiniert. Das zweite Projekt untersucht die Integrität des Hippocampus über MRI-Volumetrie-Technik, im Zusammenhang mit der Alterung. Es wurde berichtet, dass sich alte Tiere mit räumlichen Gedächtnisstörungen auf ihr Vertrautheitsurteil verlassen, um Wiedererkennungsaufgaben zu lösen.Recognition memory refers to the ability of assessment of previous occurrence. However, little is known regarding the biology that supports this function. There is a consensus that the medial temporal lobe (MTL) is necessary for recognition memory, but the exact network remains unknown. To parallel functional imaging studies in human, I first aimed at assessing the MTL areas involved after a recognition memory task based on olfactory modality in rodents. To do so, we used Fluorescent In Situ technique with the immediate early gene pre-mRNA Arc. Because the question of the hippocampal involvement in recognition memory remained unclear with the latter experiment, I designed a second project to focus only on the hippocampus. This part investigates the integrity of the hippocampus via MRI volumetry technique, in the context of aging. Additionally, this study also answers the ongoing debate of the potential volume reduction in aging and its consequences on cognitive capacities

Dynamics of Spatio-Temporal Binding in Rats

International audienceTime and space are commonly approached as two distinct dimensions, and rarely combined together in a single task, preventing a comparison of their interaction. In this project, using a version of a timing task with a spatial component, we investigate the learning of a spatio-temporal rule in animals. To do so, rats were placed in front of a five-hole nose-poke wall in a Peak Interval (PI) procedure to obtain a reward, with two spatio-temporal combination rules associated with different to-be-timed cues and lighting contexts. We report that, after successful learning of the discriminative task, a single Pavlovian session was sufficient for the animals to learn a new spatio-temporal association. This was seen as evidence for a beneficial transfer to the new spatio-temporal rule, as compared to control animals that did not experience the new spatio-temporal association during the Pavlovian session. The benefit was observed until nine days later. The results are discussed within the framework of adaptation to a change of a complex associative rule involving interval timing processes