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Accueil du site > Séminaires LNC > séminaires à venir (upcoming seminars)

Vincent Villette et Arnaud Malvache

Distance cell assemblies in the CA1 hippocampus in the absence of external landmarks

(Institut de Neurobiologie de la Méditerranée, Marseille)

Hippocampal networks can display sequences of neuronal activation either in the presence of external landmarks (visual, olfactory, auditory, and tactile) or through internal mechanisms but within a behaviorally relevant context as for example occurs during the delay period of a memory task (Pastalkova et al. 2008). Several studies have addressed the relative influence of these various external cues on the patterning of hippocampal activity. At single cell level, it is now becoming increasingly clear that neuronal activity in the CA1 hippocampus can represent location, time or distance, depending on the external cues available or the task at hand. Here we examined the spontaneous dynamics of hundreds of hippocampal CA1 neurons simultaneously and studied how spatial tuning changes in the absence of landmarks, under the sole influence of self-motion cues, in an endless environment. To this aim, we used chronic calcium imaging of activity in CA1 hippocampal neurons from head fixed mice allowed to self-regulate their motion on an empty treadmill in the absence of reward. In this talk, we will present data indicating that distance can be represented in the CA1 hippocampus in the sequential firing of recurrent and robust neuronal assemblies. This finding suggests that not only landmark-based but also self-motion navigation can be encoded within the hippocampal map.