ABSTRACT
Epileptic seizures are caused by an abnormal, synchronized firing of large populations of neurons that is usually self limiting. Epilepsy is defined as a disease in which such seizures recur. Generalized seizures are widespread. Partial seizures are initiated from one region of the cortex, typically the motor cortex, or the temporal lobe. Drugs effective on some subtypes of epilepsy fail to be effective on others, which implies that different mechanisms are at work. Cellular and molecular mechanisms that might underlie epilepsy have been studied particularly in the hippocampus. Epileptogenesis refers to the development of the hyperexcitable state that predisposes to seizures. Long-term processes postulated to be epileptogenic in acquired epilepsy are autoimmune disease and axonal sprouting. Surgical resection of sclerotic hippocampus usually cures the epilepsy, indicating that mossy fiber sprouting might cause the hyperexcitability. Normally it is extremely difficult to induce seizure-like activity in dentate granule cells, because they lack recurrent mossy fiber excitatory connections with neighboring granule cells.
