Label-free live brain imaging with third-harmonic generation microscopy

The ability to visualize neurons inside living brain tissue is a fundamental requirement in neuroscience and neurosurgery. Especially the development of an optical probe of brain morphology with micrometer-scale resolution is highly desirable, as it would provide a non-invasive approach to optical biopsies in diagnostic medicine. Two-photon laser scanning microscopy [1] is a well-established 3D-imaging technique, but requires fluorescent dyes to provide image contrast. In biomedical applications, this may lead to problems with toxicity, dye diffusion and bleaching.