Neural Correlates of Interval Timing in Rodent Prefrontal Cortex (2013) only looked at neurons with a firing rate of ≥1 Hz during the recording

Cortical ensembles orchestrate social competition through hypothalamic outputs (2022) removed neurons with a firing rate < 0.05 Hz

Electrophysiological Recording Techniques - Chapter 5: Large-Scale Neural Ensembles in Mice: Methods for Recording and Data Analysis (Hui Kuang and Joe Z. Tsien) excluded firing rate of <0.5