Septal influences on the activity of hippocampal neurones during sleep

Septal influences on CA1 and DG neurones were studied in sleeping cats before and after septal lesions suppressing the theta rhythm. Septal influences tonically gauge the activity level of a discrete group of CA1 and DG neurones, regardless of sleep stages. The observed splitting of each CA1 and DG population into two groups of units showing opposite changes in firing rate from SS to DS may be related to extraseptal inputs.