Summary
Highlights
Generalized seizures involve excessive activity arising simultaneously across widespread brain areas. While mechanisms are not fully understood, they may involve pervasive hyperexcitability of cortical neurons and abnormalities in thalamocortical networks.
Epilepsy is a chronic condition defined by recurrent seizures, which are temporary disruptions of normal brain activity due to excessive neural activity. Causes can be genetic or acquired, though often unknown.
Seizures vary greatly in appearance, from brief interruptions in consciousness to violent convulsions. A commonality, however, is excessive neural activity where groups of neurons fire simultaneously, increasing firing rates and causing large spikes in neural activity.
Focal seizures originate in a specific brain area, the seizure focus. Neurons in this area experience a large, long-lasting depolarization followed by a train of action potentials, known as a paroxysmal depolarizing shift. This activity can spread due to failed inhibitory mechanisms.