IDBR: Development of a streak microscope for measurement of fast multineuronal signals.
One of the greatest challenges in neuroscience is to understand how patterns of electrical activity in networks of neurons underlie brain function. Although the fundamental electrical signals (action potentials) and the basic hardware elements that generate these signals (neurons) are well known, the temporal (~ 1 kHz) and spatial (~10 micrometer) scales in which this signaling occurs prohibit parallel measurements from more than a small number of neurons. In recent years, new optical methods for tracking neural activity have been developed and offer great promise for overcoming some of these technical barriers. However, available microscopy methods and instrumentation are incapable of recording ensemble neural activity with sufficient spatial and temporal resolution. This proposal aims to address this issue directly by constructing a novel microscope optimized to record ensemble neuronal activity with temporal precision (> 8KHz) appropriate to resolve action potential activity in single neurons. The microscope¡¦s design is inspired by star trails observed in long exposure images of the night sky and is thus termed a fluorescent trails microscope (FTM). The FTM will be optimized to perform prolonged optical measurements of spatially distributed signals with submillisecond resolution. Rather than scanning a laser beam, the microscope will utilize a computer addressable diffractive element (a spatial light modulator or SLM) to generate continuous, patterned illumination of user-selected regions of interest. Images will be swept across a CCD or CMOS sensor in synch with the frame rate, allowing for the increased temporal resolution. This flexible design should be adaptable for use in a variety of experimental preparations including in vivo brain imaging and other biomedical applications involving time resolved fluorescence photometry. The proposed activity will foster specific cross-disciplinary, interactions and pre-college educational activities. Once fully developed, this technology will be used by a wide range of scientists at UCLA and beyond who are interested in measuring neuronal network activity as well as studying other biological phenomenon with collective properties. Construction of the instrument will involve recruitment of students in Physics from a nascent "Neurophysics Program" at UCLA who will be engaged in the interpretation of the resulting large quantity of experimental data requiring expertise in systems neurobiology and statistical physics. The project will provide a platform for students in multiple graduate disciplines (i.e., Physics, Neurobiology, Mathematics) to expand their knowledge base beyond the traditional boundaries of their respective fields as well as motivate campus wide interaction and collaboration. Lastly, there will be an opportunity for high school and undergraduate students to tour the laboratory and learn about the science behind the project, as well directly engage in the research, with a particular emphasis on recruiting those from underserved communities.
We have designed a novel type of microscope optimize to record activity at the cellular level in brain. Over the course of the two year grant we have assembled the microsope, confirmed its perfomance specifications, and tested it with a variety of neuronal preparations. We have recently been using the microscope system to record high speed activity within single neurons and to record activity in small networks of neurons. Development of these types of approaches is essential for understanding how brain circuits operate to process information because, at present, there are no adequate technical solutions that allow reserachers to record all of the relevant signals from large populations of neurons. Broader impacts of our work include the cross disciplinary training experienced by our team members, which include a graduate student in Physics and an MD/PhD fellow in Neurology. We have also embarked on collaborative projects with other research groups at UCLA so that the technology can be helpful to other projects. Finally, we have submitted a US patent application as a first step towards making the technology widely available through commercialization. We are currently finishing a scientific manuscript which will describe in detail the microscope design, include diagnostic tests of performance, and show data obtained from experimental preparations of single neurons and populations of neurons.
