So what drives drift? We looked closely at the neurons and found that a small group of them were stable. These stable neurons were more excitable than neighboring cells, making the fate of the cells predictable.

We then looked at sensory variability - controlling or varying the smells animals received each day. Again, drift persisted at the same rate - suggesting that subtle sensory variability that is not relevant to the task isn’t the driver of drift either.

We first looked at behavior - comparing similar to dissimilar speed profiles - and found that there was no difference in drift between these sets of data. Place cells drifted at the same rate in both sets of behavior, ruling out behavior as the driver of drift.