Timing differences between HFOs and interictal epileptiform discharges generated in vitro by different mechanisms in rat hippocampal slices: A novel approach

Objective To investigate the effect of generating mechanism on the relationship between interictal‐like epileptiform discharges (IEDs) and the underlying High Frequency Oscillations (HFOs; Ripples, R, and Fast Ripples, FR). Methods Synchronous spontaneous IEDs were recorded from the CA1 area of hippocampal slices from adult rats, perfused by Mg2+‐free ACSF (n = 41slices/14 animals) or 4‐aminopyridine (50 μM, n = 37slices/16 animals); IED filtering revealed Rs and FRs and several metrics were calculated and compared (amplitude, duration, relative onset, time lag, % overlap, peak frequency, peak power, FR/R). Results Longer IEDs and higher 1st Population Spike (PS) amplitude in Mg2+‐free ACSF (vs 4‐AP; P