Distance coding in CA1 region of hippocampus: Effects of pharmacological inactivation of medial septum

Mathilde Nordlund

Epsztein Lab – Neuronal coding of space and memory


Abstract: Flexible navigation towards imperceptible goals requires an internal representation of our environment, also called a cognitive map. Hippocampal place cells, through their spatially modulated activity, are good candidates to provide a neural substrate for these internal representations. The aim of this thesis was to characterize the mechanisms by which place cells integrate internal sensory information (generated by movement). To this end, we studied the distance coding of place cells using extracellular CA1 recordings in rodents navigating in linear virtual environments. We first showed that the availability of proximal visual cues influences this distance coding. Subsequently, we investigated the mechanisms by which distance coding is generated. Based on the numerous projections that place cells receive from grid cells in the medial entorhinal cortex, we hypothesized that grid cells are strongly involved in the activity of place cells under the influence of internal cues. We performed pharmacological inactivations of the medial septum, known to affect the spatial activity of grid cells. We observed a drastic decrease in the number of distance-encoding cells. Interestingly, the effect of the inactivation did not prevent the presence of position-encoding place cells. These results suggest that the distance coding of hippocampal place cells is dependent on the activity of grid cells in the medial entorhinal cortex.



Gabrielle Girardeau, rapportrice – Institut du fer à moulin UMR-S 1270, Paris
Romain Goutagny, rapporteur – LNCA UMR 7364, Strasbourg
Jean-Christophe Cassel, examinateur – LNCA UMR 7364, Strasbourg
Francesca Sargolini, Présidente – LNC UMR 7291, Marseille
Julie Koenig, co-directrice de thèse – Inmed UMR1249, Marseille
Alfonso Represa, co-directeur de thèse – Inmed UMR1249, Marseille

Jérôme Epsztein, membre invité, Inmed UMR 1249, Marseille


Tuesday, July 5th at 2pm – Inmed conference room

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