Manipulating neurons with light

Welcome to a feature of Lab Land we hope to have on a regular basis! It’s where we explain a word or phrase that is a hot topic of discussion in the science online world and particularly relevant to research going on at Emory.

Optogenetics allows researchers to stimulate specific brain cells with light. It involves introducing light-sensitive proteins from algae into the brain cells of mice, and then using a fiber optic cable to apply a laser signal to the relevant region of the brain.

Optogenetics is a leap beyond previous genetic engineering techniques that made it possible to turn on (or delete) a gene by feeding a mouse some extraneous chemical, such as the antibiotic tetracycline or the anti-hormone tamoxifen. Instead of wondering how long it takes that chemical to make its way into the brain, scientists can literally flick a switch and see near-instantaneous and localized effects.

A paragraph in a recent Nature profile of the technique’s co-inventor, Stanford psychiatrist Karl Deisseroth, neatly lays out optogenetics’ potential uses.

The technique has since been used for everything from studying the development of neural stem cells to prompting mice to recall fearful memories. Deisseroth and his team, with their focus on psychiatric conditions, have used rodent models to explore the network of brain areas that gives rise to Gafas Ray Ban outlet anxiety and have shown that one ‘hub’ controls diverse symptoms such as an elevated breathing rate and feelings of panic and discomfort. They have switched on and off the activity of mouse neurons that use the neurotransmitter dopamine, to show how they contribute to the symptoms of depression. The team has even used optogenetics to prevent cocaine-addicted rats from seeking out the drug.

Those applications sound very much like work by several neuroscience researchers at Emory! For example, Kerry Ressler’s lab recently used optogenetics to “dissect” (genetically) a group of neurons that regulate fear in the amygdala, a region of the brain long thought to be critical for fear responses.

Their results were published in June in the Journal of Neuroscience. The first author of the paper is former postdoc Aaron Jasnow, who is now at Kent State in Ohio.

Using optogenetics allowed the Emory team to define a particular group of neurons that hold the rest of the amygdala back, restraining fear responses. These neurons may be particularly attractive therapeutic targets in conditions such as PTSD (post traumatic stress disorder).

Ressler suggests that Deisseroth will be a strong candidate for a future Nobel Prize in Medicine, because of the impact optogenetics has had on several areas of neuroscience: “It has completely transformed neuroscience in about five years.”

In addition, Thomas Wichmann and colleagues at Yerkes Ray Ban outlet have used viruses to introduce the algae proteins into subcortical regions (deep within the brain) in non-human primates. Their technique was published in PLOS One.

Emory researchers interested in optogenetics have formed an affinity group/seminar series called “GLOW”, which is scheduled to restart in September. Graduate student Laura Jones, in cell biologist Art English’s lab, is the organizer.

 

 

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Quinn Eastman

Science Writer, Research Communications qeastma@emory.edu 404-727-7829 Office

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