Experiences need to be labeled during learning for further consolidation, but brain mechanisms that select experiences for lasting memory are unknown. This study determined that successive traversals in the maze were tracked by continuously drifting populations of neurons by combining large-scale neural recordings with a novel application of dimensionality reduction techniques. They recorded from many hundreds of neurons using dual-side silicon probes implanted into the hippocampal CA1 pyramidal layer of mice. The dataset contains behavioral and electrophysiology data. These data reveal that reward provides an advantage for shifting brain states and it is the awake sharp wave ripple that serves as a mechanism for selection.