Abstracts

Rationale: Burst suppression (BS) is a pattern of globally symmetric alternating high frequency activity and isoelectricity which can be induced by several forms of anesthesia. There is scattered evidence that BS may become spatially non-uniform in the setting of underlying pathology. We want investigate the effect of seizure focus to BS. Methods: We induced BS with isoflurane in a rodent and then created a neocortical epileptic focus with injection of 4-aminopyridine. BS events were recorded before and after creation of the focus using bi-hemispheric wide-field calcium imaging and a multielectrode array. Results: We find that the epileptic focus elicits a rapid alteration in the triggering, initiation, neuronal activation and propagation of BS events. Compared with the non-epileptic brain, events become triggered from the thalamus, initiate in regions uniquely outside the ictal onset zone (IOZ), elicit marked increases in multiunit activity and propagate towards the epileptic focus. Conclusions: These findings may be useful clinically as a technique to map the IOZ in patients with severe forms of focal epilepsy in preparation for local therapy.   Funding: National Science Foundation (NSF-1264948)