(A) Coronal MR image showing an iEEG depth electrode in an epilepsy patient. Three electrode channels in hippocampal CA1 are highlighted in white. Regions are colored based on an automatic segmentation procedure (reprinted from [142]). (B) Main characteristics of brain oscillations include amplitude, period, and phase (as indicated by color). Phase-amplitude coupling (PAC) describes a systematic relationship between the phase of a slow-frequency oscillation (SFO) and the amplitude of a high-frequency oscillation (HFO). R, right; L, left; f, frequency.