According to this study, researchers examined a small set of nerve cells in the brain prevents convulsive seizures in a mouse model of temporal lobe epilepsy, the most common form of epilepsy among human adults. Researchers found Inactivating this nerve-cell population also induces the same cognitive losses that characterize chronic, drug-resistant temporal lobe epilepsy in humans. This study is be published in Science.

In contrast, inactivating these cells, known to neuroscientists as mossy cells, facilitates the spread throughout the brain of the electrical hyperactivity initially localized at a seizure's onset, causing the full-blown behavioral symptoms of temporal lobe epilepsy. Epilepsy affects 65 million people worldwide, with 150,000 new cases diagnosed annually in the United States alone.

Three out of five of those affected suffer from temporal lobe epilepsy. Progressive loss of mossy cells is a hallmark of this disorder. Mossy cells are known to be damaged easily because of head trauma and decreased blood supply. Such brain injuries, in turn, increase the risk for temporal lobe epilepsy.

The role of mossy cells in epilepsy has perplexed neuroscientists for a couple of decades. And it points to an entirely new entry point for developing drugs that could bring therapeutic relief to people with chronic, drug-resistant epilepsy, a debilitating condition that not only circumscribes patients' lifestyles and occupational options but predisposes them to depression, anxiety and early death.

An electrical storm in the brain

Epileptic seizures are sometimes described as an electrical storm in the brain. These storms typically begin at a single spot in the brain, called the focus, where nerve cells for reasons that remain unclear begin repeatedly firing in synchrony. All too often they spread from the focus to widespread areas throughout the brain, a process called generalization.

The exact location of the epileptic focus in the brain varies from individual to individual. In the great majority of patients with temporal lobe epilepsy, the focus lies in the hippocampus, a much-studied, seahorse-shaped midbrain structure that's crucial to spatial navigation and to encoding new experiences into long-term memory.

In a memory test that gauges a mouse's recognition of unfamiliar objects, the epileptic mice, despite having lost more than half of their mossy cells, did fine. But they failed another test that assesses their ability to notice when a familiar object has been moved a gauge of spatial memory, which suffers a decline in chronic temporal lobe epilepsy.

Author concludes such interventions might serve as an alternative to demanding surgical procedures now employed to excise the seizure focus from patients' brains.