The areas of the cerebral cortex that are affected in mice with absence epilepsy have been pinpointed by research that also shows that transplanting embryonic neural cells into these areas can alleviate symptoms of the disease by reducing seizure activity. Absence epilepsy primarily affects children. These seizures differ from "clonic-tonic" seizures in that they don't cause muscle spasms; rather, patients "zone out" or stare into space for a period of time, with no memory of the episode afterward.