You can see a lot by looking – (Yogi Bera). This aphorism captures the power and appeal of
imaging: through the visualization of the structure or function of the object of our interest, we can learn a great deal about it. Modern imaging technologies are advancing rapidly, and are becoming important in biology, medicine, and numerous other areas of science. There are many approaches to imaging, each with its own advantages and limitations of targets and of spatial and temporal resolutions. These approaches include magnetic resonance imaging (MRI), positron emission tomography (PET), magnetoencephalography (MEG),
optical imaging, ultrasound imaging, and various types of microscopy, including both light
and electron microscopy. In this review we shall briefly sketch one particular approach to
imaging: optical imaging. We shall illustrate its use in the study of the functional organization of the mammalian brain. A more comprehensive review of optical imaging as applied to the brain can be found in Grinvald et al., 1999.