Figure 1.

Single-unit activity during interictal epileptic discharges (IEDs) in humans and mice. (A) Top: example of local field potential (LFP) recordings from two microelectrodes (red) and simultaneous corticography (ECoG; black) in patients with medically intractable focal epilepsy during epilepsy monitoring. Vertical marks indicate single units recorded by the two electrodes. Action potentials from the two single units cluster around the IEDs (arrows). (B) Examples of LFP recordings (red) from layers 2/3 of the mouse visual cortex after unilateral superfusion of bicuculline methiodide. Vertical marks (black) indicate the spikes recorded in the loose patch configuration from the contralateral, untreated hemisphere (above) and from the cortical patch treated with bicuculline (below). In the IED focus, spikes are present only at the time of the IEDs (arrows) whereas in the opposite hemisphere other spikes appear around the events. (C) Top: IED-locked raster plots and peri-event time histograms for three example units from the recordings in a human patient. The average LFP is shown in red. The cells display distinct firing modulations around the hypersynchronous event. Below, the same representation is used to show average LFP and firing activity from three units recorded in the mouse during bicuculline induced IEDs. Examples 1 and 3 come from contralateral units, Example 2 from an ipsilateral unit. The firing frequency is similarly modulated by the IEDs in both in the human and mouse recordings. Human data are reproduced with permission from Keller et al. (2010). Mouse data are reproduced with permission from Petrucco et al. (2017).