Digital lynx sx recording system

Acute hippocampal recordings were performed using a 16-channel linear silicon probe (A1x16-5mm-50-177-A16, NeuroNexus) or a 16-channel silicon tetrode rake (A2x2-tet-3mm-150-150-121-A16, NeuroNexus). Neural signals were recorded with a Digital Lynx SX recording system (Neuralynx). Broadband signals from each contact were filtered between 0.1 and 9000 Hz and recorded continuously at 32kHz. Following acquisition, signals were down-sampled to 800 Hz, bandpass filtered between 1 and 399 Hz, and common-mode referenced to remove motion artifacts. Broken channels were discarded from further analysis. Multitaper analysis (Chronux) was used to generate power spectra from all contacts. The channel with the highest ripple power (150-300 Hz frequency band) for each recording session was selected and power across the ripple band was z-scored and averaged. Signed-rank statistical analysis was performed using one-second bins centered either at the time of peak population activity during each reactivation event (AODE classifier output > 0.1, see below), at 1.5 seconds before each reactivation event, or at 1.5 seconds after each reactivation event. These datasets were also used to assess the presence of epileptiform activity (see “Analysis of possible epileptiform events” section of Supplementary Information).

EEG (filtered 0.1–500 Hz) and EMG (filtered 10–500 Hz) signals were acquired using a Neuralynx Digital Lynx SX recording system at a sampling rate of 500 Hz (Neuralynx Inc., Bozeman, Montana). Overhead video recordings were also captured to assess behavioral states.