Fluorescent microscopy versus MRI
Professor Rusty Lansford compares fluorescent microscopy, which images at the molecular level, and MRI, which images at the cellular/neural level.
There are a variety of different imaging modalities that we carry out at the Biological Imaging Center at Caltech. The head of the institute, Scott Frazier, had this grand vision of carrying out dynamic imaging. So weâ€™ve assembled a variety of microscopes that allow you to fluorescently follow these green fluorescent proteins using lasers. They are very sophisticated microscopes. Our microscopes probably cost more than most peoplesâ€™ homes. They can range anywhere from a half to a quarter million dollars and so they are very sophisticated microscopes. What is wonderful about them is that you can get this very tight resolution. Typically, the way you figure it out is the wavelength of light divided by two would be the resolution. The visible wavelength of light, letâ€™s pretend is 500 nanometers and so we can resolve structures that are about 250 nanometers. A nanometer is 1 x 10(-9) meters, so incredibly small, smaller than you can see with your naked eye. So what we try to do with that is that weâ€™ll put these under these scopes and build incubators all around them to keep a quail egg alive, warmth and proper gases and everything so they are happy, and theyâ€™ll develop normally. Weâ€™ll window the inside of the egg and see whatâ€™s going on inside that. But even with all this sophistication we can only see maybe about 2-400 microns deep. So, we have got our x and our y [axes] and itâ€™s that z. An embryo can be millimeters deep, so we cannot image everything but what we do image, we image with a very high resolution. MRI, magnetic resonance imaging, allows a slightly different approach where you can image entirely through the developing embryos in these giant MRI machines. Our MRI machines are more MRI microscopes and they have a million times higher resolution than what you would typically get in your clinical MRI. But that still only affords us resolution in that 20 to 80 micron voxel resolution. A voxel is something that measures in x, y, and z â€“ we are getting the extra depth there. So thatâ€™s very nice and we can image the tissues but weâ€™re losing the true cellular resolution. So, these are two different toys for imaging, for two different areas. One is kind of more tissue, larger but all the way through the embryo, the other one we get cut off at a certain process so we have to get more creative about what weâ€™re doing. Those are just two of many, many imaging ways in which you can get at something.
fluorescent microscopy, dynamic imaging, mri magnetic resonance imaging, mri machines, voxel, nanometers, microscopes, rusty, lansford
Professor Jeff Lichtman discusses spatial resolution in relation to a number of imaging techniques including MRI, fluorescence microscopy, and electron microscopy.
Professor Trevor Robbins describes functional magnetic resonance imaging (fMRI) technology, which is used to take detailed images of the functioning brain.
Professor Rusty Lansford explains that dynamic imaging is important because it allows researchers to examine active development rather than interpreting a series of snapshots.
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Professor Rusty Lansford describes how researchers examine avian systems by opening an egg and dynamically imaging developmental events under a microscope.
Professor Rusty Lansford explains that modern imaging techniques use four dimensions - the x, y, and z spatial coordinates, as well as one other critical variable - time.
Professor Jeffrey Lieberman discusses how neuorimaging studies are providing fresh insights into brain structures associated with schizophrenia.
Professor Jeff Lichtman examines the technique of fluorescence microscopy in terms of its benefits (e.g. exquisite resolution) and its drawbacks (e.g. confined by the wavelength of light).
Dr. Sukhi Shergill discusses difficulties in recruiting schizophrenic patients for fMRI neuroimaging studies.