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Scientists around the world have been making major improvements to CRISPR technology since its initial applications for genome engineering in 2012. (Check out our CRISPR 101 eBook for everything you need to know about CRISPR.) Like CRISPR, optogenetics has also been making headlines over the past decade. Optogenetics uses genetically encoded tools, such as microbial opsins, to control cellular activities using light. In 2015, scientists combined CRISPR and optogenetics techniques to develop a variety of photoactivatable CRISPR tools. These tools allow scientists to use light to externally control the location, timing, and reversibility of the genome editing process. Read on to learn about the various light-controlled CRISPR tools available to researchers - some readily found at Addgene.

This post is part of our Primer on Optogenetics and was contributed by guest blogger Derek Simon.

The actual experiments you do will be determined by the topic you’re interested in studying, but, in today’s post, we’ll discuss some of the important considerations you should think about when developing optogenetics behavioral experiments. There are far too many behaviors that have utilized optogenetics to be fully summarized in a short blog post, but some examples I’m personally interested in include: intracranial self-stimulation (ICSS) and place preference. The lab I work in (the Kreek lab) focuses on the neurobiology of addictive diseases, which means we are interested in circuits that mediate drug taking behavior. If a circuit reinforces behavior (activation of the circuit promotes subsequent, repeated activation), this is an approximation of reward or the sense of pleasure that the animal perceives through taking a drug. The ideal behaviors to test reinforcement are ICSS and place preference.

This post is part of our Primer on Optogenetics and was contributed by guest blogger Derek Simon.

The surgeries and standard molecular neuroscience validation experiments we discussed last week are only half of the battle when using optogentics to answer a research question. The flip side of the optogenetics coin is materials science-based. Light is delivered to your opsin through a small piece of fiber optic cable implanted into the animal’s skull (right). The fiber optic cable is threaded through—and fixed to—an optical insulator called a ferrule (below). The fiber optic cable/ferrule is inserted into the target brain region using stereotaxic surgery and cemented to the animal’s skull using dental cement (a similar procedure as implanting a guide cannula). A fiber optic patch cable is then connected from laser to ferrule to deliver light pulses to the target brain region.

This post is part of our Primer on Optogenetics and was contributed by guest blogger Derek Simon.

Optogenetics is spreading through the neuroscience community like wildfire and for good reason. For the first time in the history of neuroscience research we have a technology that allows us to show causality in neural circuits with incredible temporal and spatial precision (I’m not going to discuss the basic biology of optogenetics so if you are not familiar with it, these reviews are an excellent introduction [1-3] and openoptogenetics provides a variety of useful resources).

As optogenetics turns 10 years old, it’s easy to forget that this technique isn’t limited to neuroscience. In fact, precise light-based control of biological processes is highly useful in other fields, including synthetic biology. Addgene depositors Christopher Voigt and Jeffrey Tabor have been working on making E. coli light responsive since 2005, when Tabor was working in Voigt's lab. Years later, these classic systems continue to be optimized by Tabor’s lab, making light-controlled gene expression in E. coli easier and more robust.