Professor Jeff Lichtman discusses spatial resolution in relation to a number of imaging techniques including MRI, fluorescence microscopy, and electron microscopy.

If one is thinking about the structure of the nervous system, one has to think about the tools one uses to resolve it. With the naked eye, for example, you can resolve the structure of a brain by looking at the brain and you see it has these gyri, these big areas that fold out and fold in and you can resolve down maybe if you got very good eyes to a few parts of a millimeter maybe a tenth of a millimeter is what you could see. You are not going to see much better resolution than that, if you use a magnifying glass the resolution will be a little better, and if you use a microscope, like a fluorescence microscope you can get the resolution down to a few parts of a micron. A micron is a millionth of a meter, just to give you a rough idea of how big a micron is - a hair on your head is about 30 microns wide, and a very good microscope can see maybe a quarter of a micron in resolution, which is pretty good. But synapses are made up of little components that are much smaller than that, about ten-fold smaller than that, and those small particles cannot be resolved with a light microscope and one has to go all the way down to the electron microscope. Now, most people who have seen scientific pictures of brain studies have not seen them with any of the techniques I have just mentioned, but rather use techniques related to magnetic resonance imaging, and those techniques also have a resolution of about a millimeter, not quite as good as the human eye but it allows us to see parts of the brain that are working through the skull. Without having to do a dissection of a human being you can see the parts of the brain that are thinking so these are enormously powerful techniques, but relative to the grain of the wiring of the nervous system they're still quite crude because their pixel size or voxel, the three dimensional particles of resolution they have, are quite large relative to the fine structure of the nervous system.

spatial resolution, magnetic resonance imaging, mri, electron, fluorescence, microscope, light, millimeter, micron, jeff lichtman