Optogenetics
Optogenetics is an innovative technique that allows researchers to manipulate specific neurons within the brain using light, a significant advancement in neuroscience. This method combines genetic engineering with optical technology, enabling scientists to control neural circuits with remarkable speed and precision by inserting light-sensitive proteins known as opsins into neurons. Since its emergence in 2005, optogenetics has transformed how researchers study brain function and disorders, offering insights into conditions such as depression and autism, particularly when traditional treatments are ineffective.
Historical developments in understanding electrical activity in the nervous system laid the groundwork for this technology. Early pioneers, including Luigi Galvani and Wilder Penfield, explored brain stimulation, leading to the realization that targeted stimulation could yield more humane methods of studying brain activity than previous invasive techniques. The BRAIN Initiative, launched in 2013, further emphasizes optogenetics' potential by seeking to develop new technologies for treating neurological conditions like schizophrenia and Alzheimer’s disease. Through ongoing research, optogenetics continues to hold promise for improving the lives of individuals with various brain-related disorders.
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Optogenetics
Optogenetics is a technique used by researchers to study the brain, specifically the brain's neurons and neural circuits. It is a type of biotechnology that combines genetics and optical techniques, using light to control specific neural circuits in living brain tissue. By using light and genetic engineering, scientists are able to pinpoint and control specific neurons in the brain with higher levels of speed and precision. It is sometimes called opsin technology, referring to the opsins—or proteins—created in the neurons that respond to light. Optogenetics has allowed scientists and medical professionals to better diagnose and treat conditions related to the brain, including depression and autism, particularly when traditional treatment methods are not effective. The use of optogenetics has also been beneficial for scientists studying the brain, as they are able to better map out the brain and discover changes after major events, such as a seizure or stroke.
Background
Although the field of optogenetics is relatively new, the concepts behind the study are much older. In the late 1700s, an Italian doctor named Luigi Galvani saw that static electricity could make a dead frog's leg move. It marked the first time that scientists and researchers realized that electrical activity controls the nervous system. Despite that early discovery, it was not until the twentieth century that greater strides were made in the study of the brain. In the 1920s, Walter R. Hess, a Swiss scientist, implanted wires into cats to stimulate their brains. He was able to provoke different reactions from the cats by stimulating different areas of their brains, proving that emotion and behavior arise from electrical impulses in the brain.
Dr. Wilder Penfield, a brain surgeon working with epileptic patients, first used electrical stimulation to map the human brain in the 1930s. As brain surgery was needed in extreme cases of epilepsy, which causes seizures, Penfield wanted to map his patients' brains to determine what areas were most important to everyday life and figure out where he should and should not operate. He used electrical stimulation to map a patient's brain, which led him to discover that specific areas of the brain controlled different areas of the body. He created a diagram of his results, making the first functional map of the human brain.
As time went on, researchers began further study of electrical stimulation in the human brain, including controversial experiments involving implanting electrodes into the brains of human subjects. Ethical concerns grew over those experiments, however, and they were deemed inhumane. In 1979, Francis Crick—who was one of the neuroscientists credited for discovering the double helix—realized that a major challenge facing the study of the brain was the need to control one type of cell while leaving the rest unaffected. At the time, Crick hypothesized that scientists may be able to use light to control specific areas of the brain, but there was no clear path to doing so. It was his idea that later became the modern study of optogenetics.
Overview
Optogenetics involves altering the genetic code of the neurons by inserting special proteins called opsins. These opsins respond to light, which allows scientists to control specific sets of neurons or neurons in different locations with light. The study of optogenetics first emerged in 2005, when American neuroscientist Karl Deisseroth published a paper on the effects of light on the brain. The inspiration for his experiments came from a German research team, who in 2003 announced the discovery of a new microbial opsin made from a type of green algae that grows in ponds. When introduced into human kidney cells, the team discovered that the opsin made the cells respond to flashes of blue light. In the summer of 2004, Deisseroth and his team, which included Feng Zhang and Ed Boyden, began running experiments to introduce this new opsin to the neurons from a rat's brain. One year later, the team had created the world's first reliable technology for creating light-sensitive neurons that signalled at the speed of the brain.
Optogenetics is considered a vast improvement over previous methods of studying the brain, particularly when compared to electrical stimulation. Scientists can now better pinpoint specific neurons in the brain they want to stimulate, whereas prior methods required the entire brain to be stimulated at once. It is also considered a more humane method when compared to electrical stimulation, which often involved implanting electrodes into the brain. Scientists can now use various opsins to turn on or off specific neurons in the brain quickly and safely using various colors of light.
The study of optogenetics has the potential to affect the lives of many people, as researchers believe it can help people with a variety of brain disorders. People with conditions such as severe depression can benefit from it, particularly when no other treatment has helped them. In 2018, a team of researchers in the United States announced that they had discovered where anxiety originates in the brains of mice and how to turn it off using optogenetics. The hope is that the research can be replicated in human brains and may one day be used to treat anxiety and anxiety-related conditions. Optogenetics was also a key component in an enterprise by the administration of President Barack Obama called the BRAIN Initiative. The BRAIN Initiative, which launched in 2013, was a $300-million program that aimed to develop technologies to treat various neurological conditions, including autism, schizophrenia, and Alzheimer's disease.
Bibliography
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Deisseroth, Karl. "Optogenetics." Nature Methods, 20 Dec. 2010, web.stanford.edu/group/dlab/media/papers/deisserothnature2010.pdf. Accessed 25 Feb. 2018.
Deisseroth, Karl. "Optogenetics: Controlling the Brain with Light." Scientific American, 20 Dec. 2010, www.scientificamerican.com/article/optogenetics-controlling. Accessed 25 Feb. 2018.
Dovey, Dana. "Hidden Origin of Anxiety Discovered in the Brain—and Scientists Now Know How to Stop It." Newsweek, 2 Feb. 2018, www.newsweek.com/origin-anxiety-cells-brain-mice-optogenetics-798105. Accessed 25 Feb. 2018.
Guru, Akash, et al. "Making Sense of Optogenetics." International Journal of Neuropsychopharmacology, vol. 18, no. 11, Oct. 2015.
"Introduction to Optogenetics." News-Medical, 7 Nov. 2017, www.news-medical.net/life-sciences/Introduction-to-Optogenetics.aspx. Accessed 25 Feb. 2018.
Lim, Diana H., and Jeffrey LeDue. "What Is Optogenetics and How Can We Use It to Discover More about the Brain?" Frontiers for Young Minds, 20 Sept. 2017, kids.frontiersin.org/article/10.3389/frym.2017.00051. Accessed 25 Feb. 2018.
Stanley, Jay. "Optogenetics: A Virtual Reality System for Controlling Living Cells." TechSpot, 29 Nov. 2017, www.techspot.com/article/1531-optogenetics/. Accessed 25 Feb. 2018.