Distinct patterns of electrical stimulation of the basolateral amygdala influence pentylenetetrazole seizure outcome

Our working hypothesis is that constant interpulse interval (IPI) electrical stimulation would resonate with endogenous epileptogenic reverberating circuits, inducing seizures, whereas a random interinterval electrical stimulation protocol would promote desynchronization of such neural networks, producing an anticonvulsant effect. Male Wistar rats were stereotaxically implanted with a bipolar electrical stimulation electrode in the amygdala. Pentylenetetrazole (10mg/ml/min) was continuously infused through an intravenous catheter to induce seizures while four different patterns of temporally coded electrical stimulation were applied: periodic stimulation (PS), pseudo-randomized IPI stimulation (LH), restrictively randomized IPI stimulation (IH), and bursts of 20-ms IPIs (burst). PS decreased the pentylenetetrazole threshold to forelimb clonus, whereas IH increased the threshold to forelimb clonus and to generalized tonic-clonic seizures. We hypothesize that PS facilitates forelimb clonus by reverberating with epileptogenic circuits in the limbic system, whereas IH delays forelimb clonus and generalized tonic-clonic seizures by desynchronizing the epileptic neural networks in the forebrain-midbrain-hindbrain circuits.