To make the proteins respond to light, the researchers harnessed Cmn, a photo-responsive amino acid. When a pulse of light shines on Cmn, it's bulky side chain breaks off, leaving cysteine, a smaller amino acid. This image was shared by the Flickr user JaredZammit. Look to notes below for more photo info.
New approach holds promise of better treatment options for severe episodes.
UC Irvine neuroscientists have developed a way to stop epileptic seizures with fiber-optic light signals, heralding a novel opportunity to treat the most severe manifestations of the brain disorder.
Using a mouse model of temporal lobe epilepsy, Ivan Soltesz, Chancellor’s Professor and chair of anatomy & neurobiology, and colleagues created an EEG-based computer system that activates hair-thin optical strands implanted in the brain when it detects a real-time seizure.
These fibers subsequently “turn on” specially expressed, light-sensitive proteins called opsins, which can either stimulate or inhibit specific neurons in select brain regions during seizures, depending on the type of opsin.
The researchers found that this process was able to arrest ongoing electrical seizure activity and reduce the incidence of severe “tonic-clonic” events.
“This approach is useful for understanding how seizures occur and how they can be stopped experimentally,” Soltesz said. “In addition, clinical efforts that affect a minimum number of cells and only at the time of a seizure may someday overcome many of the side effects and limitations of currently available treatment options.”
Study results appear online in Nature Communications.
More than 3 million Americans suffer from epilepsy, a condition of recurrent spontaneous seizures that occur unpredictably, often cause changes in consciousness, and can preclude normal activities such as driving and working. In at least 40 percent of patients, seizures cannot be controlled with existing drugs, and even in those whose seizures are well controlled, the treatments can have major cognitive side effects.
Although the study was carried out in mice, not humans, Soltesz said the work could lead to a better alternative to the currently available electrical stimulation devices.
Notes about this optogenetics and epilepsy research
Postdoctoral scholars Esther Krook-Magnuson and Caren Armstrong and staff researcher Mikko Oijala with UC Irvine’s Department of Anatomy & Neurobiology also contributed to the study, which was supported by the National Institutes of Health (grant NS074702), the Epilepsy Foundation and the George E. Hewitt Foundation for Medical Research.
Contact: Tom Vasich – University of California, Irvine Source:UC Irvine press release Image Source: The fiber optics image is adapted from an image at Flickr by the user JaredZammit. The image is shared with the CC BY-SA 2.0 license. Original Research: Open access research article for “On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy” by Esther Krook-Magnuson, Caren Armstrong, Mikko Oijala and Ivan Soltesz in Nature Communications 4:1376 published 22 January 2013 doi: 10.1038/ncomms2376