Fig. 3.

Robotic navigation algorithm for avoiding blood vessels during regional pipette localization in vivo. A: schematic showing vascular avoidance preparation. Brain outline from the Allen Mouse Brain Atlas (Lein et al. 2007). The image was generated with a downloadable application on MacOS. The application can be downloaded at http://mouse.brain-map.org/static/brainexplorer. B: visual algorithm of vascular avoidance. Obstruction (1; here a blood vessel) is detected by an increase in pipette resistance. The pipette is retracted to z_dodge (2), moved laterally (3), and advanced to the original z_obstruction (4). If the difference in resistance at z_obstruction and the resistance at z_dodge is <200 kΩ, the pipette is advanced through z_obstruction (5) and the pipette is moved back to the original x- and y-axes (6). C: the pipette is navigated around a blood vessel with sequential steps sampling from a spiral pattern. Blood vessel in A and B shown in isometric view. Blood vessel in C shown in top view (top) and cross section (bottom).