FIGURE 7.

Anterior callosotomy prevents bilateral seizure spread. (A) Sequential light images of the coronal sections show callosotomy (red arrows, magnified views) from anterior to posterior cortex (A–F, relative brain locations in B). (B) A schematic of the callosotomy, sagittal view, illustrates knife placement (red), cut genu of the corpus callosum (gcc), and uncut splenium (scc). (C) Cobalt and EEG electrodes (red dots) were positioned in the right and left anterior and posterior cortices. (D) EEG of a seizure that was recorded in mice without callosotomy. Red arrows indicate seizure onset. (E) Representative EEG of a first seizure that was recorded after callosotomy in mice with cut genu with no seizure recorded in the left premotor cortex (red rectangle). (F) Onset oflater seizures was delayed in mice with cut genu. (G) Light image of the callosotomy where only the body of the corpus callosum was cut and the genu remained intact (red arrow). (H) Seizure onset delay (seconds) in the left premotor cortex (L ctx) after callosotomy in mice with cut genu (green) and in mice with body callosotomy and intact genu (red). (I) Mice with body callosotomy and intact genu had immediate seizure onset in the left premotor cortex just like the mice without callosotomy. EEG = electroencephalography.