sentence: These results , taken together with previous findings ,11 suggest that the notion that at least 4 – 10 cm of synchronously active cortex is necessary to observe epileptiform discharges on the scalp47 , 48 does not hold for ripples.28 Moreover , icEEG studies showed that ripples are focal events that can appear in individual subdural contacts or be asynchronously present in different contacts.3 , 11 , 49 We thus may speculate that ripples on HD ‐ EEG or MEG reflect multiple focal generators asynchronously activated within a short latency , while focal ripples on individual icEEG contacts ( which constitute the majority of icEEG ripples in children with refractory epilepsy ) 3 are most likely missed by HD ‐ EEG or MEG due to spatial undersampling .