Figure 7.

Categorical analysis of hippocampal place fields in STD and ALT sessions. a, b, The pie charts show distribution of response categories between session pairs in CA1 (a), and CA3 (b) cells. Dotted lines indicate a statistically significant difference between a session pair. Stable responses were common in both CA1 and CA3 between repeated STD sessions. Stable responses were also common in CA3 cells between repeated ALT sessions, regardless of improved memory performance across these sessions. Two significant changes were observed between the first and second ALT sessions in CA1 fields: 47% were stable between the first and second ALT sessions, and the stability increased significantly in later sessions (see increased Stable category during ALT2-ALT3, second row). Twenty-nine percent of CA1 fields were stable between STD1 and ALT1 sessions, and the stability increased significantly in later STD and ALT comparisons (bottom row). In CA3, most cells had a place field in either STD or ALT, but not both (b, bottom row).