People having a gelastic seizure (GS) sound like they are laughing or mumbling. This is an uncontrolled reaction caused by unusual electrical activity in the part of the brain that controls these actions. Gelastic seizures are named after the greek word for laughter, "gelastikos." GS often occurs in patients with hypothalamic hamartomas (HH). HH is a rare, non-cancerous brain tumor on the hypothalamus. Symptoms The most common sign of GS is the patient startling. Patients may also have a look of