Stopping seizures is as simple as turning on a light (and some genetics)

What if you change your mind with the flip of a light switch?  Over the past decade, optogenetics has become an important component of neuroscience research.  By introducing genes that code for fast light-activated proteins (opsins) into a specific cell-type, researchers can shine a certain color of light onto living tissue to activate these opsins and examine how those specific cells’ activity modulates behavior in real-time.  For example, light-activation of specific neurons in the motor cortex of a mouse causes it to only make right turns, but otherwise behave normally when the light is off.  Thus, optogenetics is a great tool to see how neural activity is coordinated with behavior.

Optogenetics

What if you could stop a seizure with light?  In a recent paper from the laboratory of Ivan Soltesz, Ph.D. at UC Irvine, optogenetics was used to treat epileptic mice.  EpilepsyA nervous system disorder that causes seizures due to abnorm... More is a disorder of recurrent spontaneous seizures, which result from abnormal, excessive, or hyper-synchronous neuronal activity.  It is hypothesized that if you can reduce this excitable state, epilepsies may be able to be controlled.  In this study, mice were genetically modified to express the light-activated protein called halorhodopsin, which inhibits neurons so they cannot fire action potentials, in excitatory principle cells of the hippocampusStructure in temporal lobe that has many functions but is es... More.  The researchers used an optical fiber to deliver a laser light into the hippocampus of mice that had form of epilepsy called temporal lobe epilepsy (TLE).  Within five seconds of laser light activation, seizureAn event that is associated with uncontrolled and excessive ... More duration was significantly reduced by half!  Seizure control was also achieved when excitatory opsins called channelrhodopsin were selectively expressed in a subpopulation of GABAergic inhibitory cells that make up <5% of neurons in the hippocampus.  The results of this study show that spontaneous seizures can be terminated by directly inhibiting overly excited seizing neurons or by activating inhibitory neurons within a specific brain region.

Mouse Seizure Optogenetics

This study is significant because it opens the door to developing novel optogenetic treatments for epilepsy.  Modulating the activity of specific neurons in a temporally and spatially selective manner is better than the brain-wide effect that seizure-reducing medications offers.  While we are perhaps a long way from treating epileptic people, a clinical approach based on the principles established in this study may overcome many of the side effects of current treatment options.  Hopefully, future improvements in geneA sequence of nucleic acids that forms a unit of genetic inh... More therapy methods and light stimulation will be able to help overcome these obstacles and pave the way for a whole new class of optogenetics-based therapies in patients with epilepsy and other neurological disorders.

Check back later this week for more about epilepsy and optogenetics!

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Krook-Magnuson, E., Armstrong, C., Oijala, M., & Soltesz, I. (2013). On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy. Nature Communications, 4 DOI:10.1038/ncomms2376
Images adapted from Andrzej Wojcicki/Science Photo Library/Corbis and made by Kate Jones.

Kate Fehlhaber

Kate graduated from Scripps College in 2009 with a Bachelor of Arts degree in Neuroscience, completing the cellular and molecular track with honors. As an undergraduate, she studied long-term plasticity in models of Parkinson’s disease in a neurobiology lab at University of California, Los Angeles. She continued this research as lab manager before entering the University of Southern California Neuroscience graduate program in 2011 and then transferring to UCLA in 2013. She completed her PhD in 2017, where her research focused on understanding the communication between neurons in the eye. Kate founded Knowing Neurons in 2011, and her passion for creative science communication has continued to grow.

Latest posts by Kate Fehlhaber (see all)

Kate Fehlhaber

Kate graduated from Scripps College in 2009 with a Bachelor of Arts degree in Neuroscience, completing the cellular and molecular track with honors. As an undergraduate, she studied long-term plasticity in models of Parkinson’s disease in a neurobiology lab at University of California, Los Angeles. She continued this research as lab manager before entering the University of Southern California Neuroscience graduate program in 2011 and then transferring to UCLA in 2013. She completed her PhD in 2017, where her research focused on understanding the communication between neurons in the eye. Kate founded Knowing Neurons in 2011, and her passion for creative science communication has continued to grow.

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