Laminar distribution of electrically evoked hippocampal short latency ripple activity highlights the importance of the subiculum in vivo in human epilepsy, an intraoperative study

•HFOs can be evoked by parahippocampal stimulation in all subfields of the human hippocampus.•Inhalational anesthetics (isoflurane) suppressed HFO generation compared to propofol.•Subiculum was active in coincidence with the severity of HS, signifying its importance in TLE. The goal of this study was to define the pathology and anesthesia dependency of single pulse electrical stimulation (SPES) dependent high-frequency oscillations (HFOs, ripples, fast ripples) in the hippocampal formation. Laminar profile of electrically evoked short latency (250 Hz) in the other subregions indicate the pathological nature of these evoked oscillations. Subiculum was found to be active producing HFOs in parallel with the cell loss in the hippocampus proper, which emphasize the role of this region in the generation of epileptic activity.