Several laboratories are now using Focused Ion Beam Scanning Electron Microscopes (FIB-SEM) to image small volumes of plastic embedded brain tissue at resolutions approaching 5x5x5nm voxel size. The fact that FIBSEM can obtain such resolution is of fundamental importance since at this resolution all neuronal processes should be traceable with 100% accuracy using fully automatic algorithms. A fundamental physical limitation of the FIB ablation process is that this resolution can only be obtained for very small samples on the order of 20 microns across. To overcome this limitation Ken Hayworth has developed a technique using a heated, oil-lubricated, ultrasonically vibrating diamond knife which can section large blocks of plastic-embedded brain tissue into 20 micron thick strips optimally sized for high-resolution FIB-SEM imaging. Crucially, this thick sectioning procedure results in such high-quality surfaces that the finest neuronal processes can be traced from strip to strip.