This program announcement (PA) solicits Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) grant applications that propose research and development of probes useful in imaging the structure and function of the brain and other parts of the nervous system, with award duration and amounts greater than those routinely allowed under the SBIR/STTR programs. Specifically this PA solicits SBIR/STTR applications that propose research and development of probes that generate signals detectable by one or more imaging modality. Such probes should indicate the structure or function of molecules or subcellular elements of neurons or other cells of the nervous system. Of special interest are applications that propose research and development of novel probes, although significant enhancements of already existing probes are also solicited. Grant applications may propose projects that will result in probes solely intended for use in research or probes that might have clinical utility. It is expected that this initiative will require expertise from a variety of disciplines, including neuroscience, biology, chemistry, physics, engineering, biotechnology, and bioengineering. Moreover, it is anticipated that these types of expertise will be brought together in various combinations in individual proposed projects.