Figure 2. EEG recordings during non-lethal seizures, terminal seizures, and interictal periods in Fhf1^R52H/+ mice.

A) Scheme for all three-channel EEG recordings. RF (right frontal, sensorimotor) and LO (left occipital, visual) were unipolar mounts versus a reference electrode (R; an anchoring jeweler’s screw) in the nasal bone. The third channel is LF-RO (left frontal vs. right occipital, a bipolar mount). Common ground was placed in the skull above the cerebellum (anchoring jeweler’s screw). B) Baseline recording during awake period. Low amplitude fast activity beta waves were abundant in all channels. C) A non-lethal seizure. This mutant mouse had four seizures between P19-P21. One of the non-lethal seizures initiated coincident with a body twitch (arrowhead) followed by a tonic-clonic seizure with typical EEG signature consisting of fast spikes followed by spike-and-wave activity with slowing and decrease in amplitude and a period of post-ictal suppression (not shown). D) Interictal spikes. The same animal as in (C) had frequent interictal spikes (asterisks) without behavioral correlates. E) Terminal seizure. In the same animal as in (C) and (D), a final interictal spike (asterisk) preceded a body twitch (arrowhead) and tonic-clonic seizure with fast spike and spike-and-wave phases indistinguishable from a preceding non-lethal seizure (C). F) Terminal seizure with muted EEG signature. This mutant experienced near-identical behavioral signature preceding death as in (E) commencing with body twitch (arrowhead) and a similar late spike-and-wave phase, but fast spikes were not readily detected.