Explore cutting-edge tools for mapping and repairing neural circuitry in this first part of a three-part lecture by MIT Professor Ed Boyden. Delve into the innovative technique of expansion microscopy, which allows for unprecedented visualization of brain structures. Learn how this method enables nanoscale imaging of microtubules, inhibitory synapses, and the nuclear envelope. Discover the challenges of understanding the brain and how expansion microscopy addresses these by physically enlarging tissue samples. Gain insights into vector field calculations, distortion correction, and the potential of this technique to reveal previously unknown information about neural structures. This lecture, part of a series on advanced neuroscience tools, provides a comprehensive introduction to expansion microscopy and its applications in unraveling the complexities of the brain.