This project will investigate how new forms of light may enhance the electrical output and control of neurons that have been genetically modified to be light-sensitive. Optogenetics is a rapidly developing field that uses molecular biology techniques to enable cellular functions to be controlled with light. When neurons (nerve cells) are genetically modified to express a light-activated membrane channel, they can be made to trigger electrical activity when exposed to light. This new level of light-activated control over neuronal activity has yet to be fully exploited, but is offering new opportunities for understanding how neurons and their electrical circuits function within the brain to form thoughts, memories, behaviors, and emotions. In optical science and engineering, advances now make it possible to generate a wide range of new forms of light with customized properties, or what is called tailored light. This research is highly significant and important for the fields of neuroscience and biophotonics. Biophotonics is the science of how light interacts with biological cells and tissues, and neuroscientists seek to understand how the brain and mind work. The new optical sources for generating tailored light in this project will change the way in which we use optogenetics to investigate and understand the function of neurons, neural circuits, and the brain. This project is also highly interdisciplinary, and will provide a unique educational and training opportunity for undergraduate and graduate students to help them solve the complex interdisciplinary problems in engineering and biology in the future. Results from this research will also be integrated into undergraduate and graduate courses in biophotonics, neuroscience, and advanced microscopy. The long-term societal benefits of this research will include raising the public's scientific literacy of how neurons and neural circuits in our brain function, and how new types of light and lasers can be used to probe the complex functions of our brain.
Optogenetics is a rapidly expanding field, and one that originated out of the field of neuroscience, where genetic modifications to mammalian neurons enabled photo-activated control of membrane channels to elicit action potentials. While this concept has provided a unique toolkit for exploring neuroscience questions and envisioning new medical science applications, there have been relatively few advances or contributions to optogenetics from the fields of optical science and engineering. This proposal addresses this gap by using advanced optical sources and precise control over the optical properties of the light stimuli to enhance the neural control in optogenetics.
The innovation of this research project is the ability to generate new forms of tailored light, and apply this light as new forms of stimuli to excite, modulate, and control the output of optogenetically-modified neurons in new ways. Conceivably, it is much more practical to modify and control the light stimulus than to genetically modify the biological properties of cells and tissues. As optogenetics advances to in vivo applications, this practical advantage will be even more significant. Therefore, our hypothesis is that by precisely controlling the spectral, temporal, and spatial parameters of novel tailored light stimuli, it is possible to provide enhanced modulation and control of the electrical output activity of optogenetically-modified neurons. To prove our hypothesis, our research plan will be guided by three objectives. First, we will construct an optical stimulus and microscope system to generate these new forms of tailored light. Second, we will optically stimulate and electrically/optically record from cultured hippocampal neurons that have been genetically modified to express Channelrhodopsin-2, a light-gated membrane ion channel, to investigate how tailored light stimuli alters the electrical output and activity from these cells. Third, we will implement an optical feedback system that will measure the optical response of the neurons and adjust the light stimuli parameters to optimize, modulate, and control the electrical output.
The successful outcome of this research project will have far-reaching impact in not only the field of biophotonics, but also in neuroscience and optical science and engineering. Just as optogenetics is expected to make a broad impact in neuroscience, as well as medical science, this research will potentially have an even greater and more rapid impact because it will conceivably be more practical to tailor the light stimulus than to modify the biology to enhance the optogenetic control in the future.
This award is being made jointly by two Programs- (1) Biophotonics, in the Division of Chemical, Bioengineering, Environmental and Transport Systems (Engineering Directorate), and (2) Instrument Development for Biological Research, in the Division of Biological Infrastructure (Biological Sciences Directorate).
