Neurogenesis in Epilepsy

by Rabiya S. Tuma

November, 2006

New neurons arise in certain regions of the brain throughout a person’s life in a process called neurogenesis. One region where many neurons arise is the dentate gyrus, a region that is damaged by temporal lobe epilepsy.

This common location for the birth of new neurons and neural death due to seizures led many researchers to hypothesize that the young neurons may naturally help repair the damage, or might be induced to do so by physicians. New findings suggest otherwise, however.

Helen Scharfman, a neurologist at Columbia University and the Center for Neural Recovery and Rehabilitation Research at Helen Hayes Hospital in West Haverstraw, New York, has found in animal models that seizures do trigger neurogenesis but that the young neurons do not become wired properly into the system. When her research team measured the electrical activity of these young neurons, they found abnormal behavior: wiring to the wrong partners, becoming hyper excitable relative to their healthy neighbors, and acting in a synchronous manner, the last of which is also seen during seizures. Additionally, the number of new neurons correlated with the frequency of seizures.

“The new neurons may not be reparative but [rather] may be part of the problem,” Scharfman said. But there may be a bright side: “If we get rid of some of these we might help people with epilepsy.” The abnormal wiring might also explain some of the depression and learning problems associated with epilepsy.

Scharfman’s group is now looking for ways to reduce the number of these new neurons to see if the animals have fewer seizures.