Distal tuft dendrites predict properties of new hippocampal place fields.

Hippocampal pyramidal neurons support episodic memory by integrating complementary information streams into new "place fields." Distal tuft dendrites have been proposed to drive place field formation via dendritic plateau potentials. However, the relationship between distal dendritic and somatic activity is unknown in vivo. Here, we gained simultaneous optical access to distal tuft dendrites and their soma in head-fixed mice navigating virtual reality environments. While distal tuft dendrites rarely express local peri-formation plateau potentials, the timing and extent of their recruitment predict properties of resultant somatic place fields. Following somatic place field formation, distal tuft dendrites readily express plateau potentials as well as local place fields that are back shifted relative to that of their soma. Distal tuft dendrites may therefore undergo local plasticity during somatic place field formation. Through direct in vivo observation, we provide an updated dendritic basis for hippocampal feature selectivity during navigational learning.