Synapse in epilepsy. Illustration of a nerve cell junction (synapse) and neurotransmitters (red spheres) in epilepsy. Epileptic seizures are caused by abnormal electrical activity in the brain. The normally ordered electrical activity associated with brain function becomes chaotic and unregulated during a seizure. In some cases, a stimulus, such as flashing lights, can trigger an attack, but normally there is no apparent cause. Epilepsy is thought to be caused by disease or injury, and may also be inherited. A number of neurotransmitters are thought to be involved in epilepsy.