Multiple coordinated cellular dynamics mediate CA1 map plasticity

Abstract

In the hippocampus, spatial and nonspatial information are jointly represented as a neural map in which locations associated with salient features are over-represented by increased densities of relevant place cells. Although we recently demonstrated that experience-dependent establishment of these disproportionate maps is governed by selective stabilization of salient place cells following their conversion from non-place cells, the underlying mechanism for pre-established map reorganization remained to be understood. To this end, we investigated the changes in CA1 functional cellular maps imaged using two-photon calcium imaging in mice performing a reward-rearrangement task in virtual reality. Mice were pre-trained on a virtual linear track with a visual landmark and a reward in two distinct locations. Then, they were re-trained on the same track with the exception that the location of reward was shifted to match the landmark location. We found that, in contrast to de novo map formation, robust map reorganization occurred through parallel coordination of new place field formation, lateral shifting of existing place fields, and selective stabilization of place fields encoding salient locations. Our findings demonstrate that intricate interplay between multiple forms of cellular dynamics enables rapid updating of information stored in hippocampal maps.