Mean normalized lap-based field width ± SE of CA1 and CA3 place fields in familiar and novel sessions for all 4 days combined.

Regression lines are depicted on top of the raw data. CA1 place fields tended to increase in size over laps in the familiar environment, but not in the novel environment. Conversely, CA3 place fields tended to decrease their size, but this effect was not significant in the familiar environment and was only marginally significant in the novel environment. Significance levels of linear regression are indicated: *p = 0.055, **p<0.005.