UT Arlington assistant professor of physics Dr. Samarendra Mohanty, Ph.D. has, with his research team co-authors Kamal Dhakal, Ling Gu, and Bryan Black, published a paper entitled “Fiber-optic two-photon optogenetic stimulation” in the journal Optics Letters, describing development of a development of a “fiber-optic, two-photon, optogenetic stimulator” and its use on human cells in a laboratory.
The paper’s abstract notes that optogenetic stimulation of genetically-targeted cells is proving to be a powerful tool in the study of cellular systems, both in-vitro as well as in-vivo. However, the researchers note that most opsins are activated in the visible spectrum where significant absorption and scattering of stimulating light occurs leading to low penetration depth and less-precise stimulation, adding that since they first demonstrated two-photon optogenetic stimulation (TPOS), their findings are gaining considerable interest in the probing of cellular circuitry by precise spatial modulation, but that, all existing methods have been using microscope objectives and complex scanning beam geometries. In this paper, they report a non-scanning method based on that multimode fiber to accomplish fiber-optic two-photon optogenetic stimulation (FO-TPOS) of cells.
The tiny tool builds on a previous discovery of Dr. Mohanty’s that near-infrared light can be used to stimulate a light-sensitive protein introduced into living cells and neurons in the brain, and that his new method could show how different parts of the brain react when a linked area is stimulated.
“The technology would be useful in the BRAIN mapping initiative recently championed by President Barack Obama, Dr. Mohanty says in a UTA release. “BRAIN stands for Brain Research Through Advancing Innovative Neurotechnologies and will include $100 million in government investments in research. Scientists have spent a lot of time looking at the physical connections between different regions of the brain. But that information is not sufficient unless we examine how those connections function,” he continues. “That’s where two-photon optogenetics comes into play. This is a tool not only to control the neuronal activity but to understand how the brain works.”
The fber-optic two-photon optogenetic stimulation described in the eponymous Optics Letter paper involves introducing the gene for ChR2, a protein that responds to light, into a sample of excitable cells. A fiber-optic infrared beam of light can then be used to precisely excite the neurons in a tissue circuit. In the brain, researchers would then observe responses in the excited area as well as other parts of the neural circuit. In living subjects, scientists would also observe the behavioral outcome, Dr. Mohanty explains.
A particular advantage of Optogenetic stimulation cited is that it avoids damage to living tissue by using light to stimulate neurons instead of the electric pulses used in past research. Dr. Mohanty’s method of using low-energy near-infrared light also enables more precision and a deeper focus than the blue or green light beams often used in optogenetic stimulation, the paper notes.
Using fiber optics to deliver the two-photon optogenetic beam is another advance in methodology over the bulky microscopes and complex scanning beams previously employed. Dr. Mohanty’s group is collaborating with UT Arlington Department of Psychology assistant professor Linda Perrotti to apply this technology in living animals.
“Dr. Mohanty’s innovations continue to be recognized because of the great potential they hold,” Pamela Jansma, dean of the UT Arlington College of Science observes in the UTA release. “Hopefully, his work will one day provide researchers in other fields the tools they need to examine how the human body works and why normal processes sometimes fail.”
The University of Texas at Arlington, with a campus spanning 420 acres and including more than 100 buildings — some dating from 1919 — and an enrollment approaching 33,500, is the second largest institution in the UT System and the sixth largest in Texas.
UT Arlington’s stated goal is to become one of America’s premier research institutions, with research activity at the institution having more than tripled to $66 million over the past 10 years, with increasing expertise in bioengineering, medical diagnostics, micro-manufacturing, and defense and Homeland Security technologies, among other areas.
Students and faculty work at some of the most advanced learning environments in Texas, including the clean room in the Nanotechnology Research & Education Center (NanoFab lab – see our recent BioNews Texas report here), the kilns in UTA’s glass-blowing studios, the neonatal intensive care unit in their Smart Hospital, and the brain injuries laboratory in the Maverick Activities Center.