The development of behavioral and neuronal activities of animal models with kindling-induced and spontaneous temporal lobe seizures

Epilepsy, in terms of the sudden and recurrent malfunction of brain caused by abnormal discharge, is called “seizure”. Recently, experiments on animal models have successfully demonstrated the better understanding of the excitability of neuronal networks in relation to the occurrence of seizures. In this work, the developments of behavioral and neuronal activities of kindling-induced and spontaneous temporal lobe epilepsy (TLE) in rats were investigated. Daily stimulation of the right-side amygdala was delivered to Wistar rats to induce TLE. Each kindling evokes the excited neuronal activities in the brain. The duration, spike density and amplitude of evoked discharges were increased during kindling procedure. With repeated 40 stimulations, the rats showed the progression from tonic seizures (stage-1,2) to generalized clonic- tonic convulsive seizures (stage-4,5). In a consequence, the daily stimulation causes the permanent brain function damage and three rats were successfully induced to have spontaneous TLE of seizure stage-2. The cortical neuronal activities exhibit high voltage rhythmic spike (HVRS) discharges oscillating in the rage of 9-11 Hz and 18-21 Hz (second harmonics). HVRS is characterized by a barrage of large spike discharge (80-400μV) with negative polarity. It was found that the inter-spike interval (ISI) between two negative spikes is positively correlated (r=0.9852) to the amplitude of former spike in a HVRS episode. A large amplitude spike was accompanied by a long ISI, while a small amplitude spike took place in group with a short ISI. The investigation on cortical epileptiform is practical to develop the on-line seizure detection algorithms. With integration of an electrical stimulator or drug delivery device, such a seizure warning system or a closed-loop seizure control device could enhance the patients’ life quality.