Effects of direct brain stimulation depend on seizure dynamics

Brain stimulation is currently used as an experimental treatment for patients with medically refractory epilepsy. However, the results of such stimulation are still less than optimal. A major factor is the lack of understanding of the mechanisms of applied stimuli. Herein we review evidence on the effects of stimulation in models of epileptic seizures. We show that the effects of stimulation during epileptic seizures can differ from those observed under normal conditions. Several studies suggest a potentially greater beneficial therapeutic effect of strong depolarizing and overactivating stimulations than hyperpolarizing ones in the treatment of seizures. The potential relevance of these results to other therapeutic stimulation protocols is discussed.