Article by The Transmitter
Five years ago, while working to develop a tool to label neurons that are active during seizures in mice, Dr. Quynh Anh Nguyen, assistant professor of pharmacology at Vanderbilt University, noticed something she had not seen before. “There was a particular region in the brain that seemed to ‘light up’ really prominently,” she says. Nguyen had induced seizures in the animals by injecting kainic acid into the hippocampus—a common strategy to model temporal lobe epilepsy. The condition often involves hyperactivity in the anterior and middle regions of the hippocampus, but Nguyen’s mice also showed the activation in a tiny posterior part of the hippocampus called the fasciola cinereum. Despite the subregion’s obscurity, it looked to be an important and previously overlooked contributor to epilepsy in people who do not respond to anti-seizure medications or tissue ablation in the hippocampus, Nguyen and her colleagues say. Inhibiting fasciola cinereum neurons optogenetically (enabling them to be controlled using light) shortens the duration of seizures in model mice, that study also shows. A case study also showed that seizures decreased in frequency in one participant who underwent ablation to remove the subregion, hinting that the fasciola cinereum could serve as a novel treatment target. To further translate the results from mice to people, study investigator Dr. Ryan Jamiolkowski, a neurosurgery resident at Stanford, decided to try putting stereoelectroencephalography (sEEG) electrodes used to localize the source of hyperactivity in a brain in the active fasciola cinereum neuron region of six people with drug-resistant epilepsy. All six people showed seizure activity in the fasciola cinereum. One participant had already undergone surgery to ablate the anterior hippocampus and amygdala but was still experiencing a high volume of seizures. Ablating the fasciola cinereum, however, decreased the participant’s seizure frequency by 83 percent after 18 months, reinforcing the involvement of this area.