Cranial microsurgery is an essential procedure for accessing the brain through the skull that can be used to introduce neural probes that measure and manipulate neural activity. Neuroscientists have typically used tools such as high-speed drills adapted from dentistry to perform these procedures. As the number of technologies available for neuroscientists has increased, the corresponding cranial microsurgery procedures to deploy them have become more complex. Using a robotic tool that automatically performs these procedures could standardize cranial microsurgeries across neuroscience laboratories and democratize the more challenging procedures. We have recently engineered a robotic surgery platform that utilizes principles of computer numerical control (CNC) machining to perform a wide variety of automated cranial procedures. Here, we describe how to adapt, configure and use an inexpensive desktop CNC mill equipped with a custom-built surface profiler for performing CNC-guided microsurgery on mice. Detailed instructions are provided to utilize this ‘Craniobot’ for performing circular craniotomies for coverslip implantation, large craniotomies for implanting transparent polymer skulls for cortex-wide imaging access and skull thinning for intact skull imaging. The Craniobot can be set up in <2 weeks using parts that cost <$1,500, and we anticipate that the Craniobot could be easily adapted for use in other small animals.
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S.B.K. acknowledges funds from the Mechanical Engineering Department, College of Science and Engineering, MnDRIVE RSAM initiative of the University of Minnesota, Minnesota Department of Higher Education and NIH 1R21NS103098-01, 1R01NS111028, 1R34NS111654, 1R21NS112886 and 1R21 NS111196. L.G. was supported by the University of Minnesota Informatics Institute’s (UMII) graduate fellowship. We thank Dr. Eric Yttri, Alan Lai and Mark Nicholas of the Yttri laboratory at Carnegie Mellon University for useful feedback during beta-testing of the Craniobot. We also thank Luiz Bueno and Dr. York Winter of labmaker.org, who provided insights and suggested improvements to streamline hardware assembly. We also thank Dr. Spencer Smith (@Labrigger) for discussions on automated technologies for cranial microsurgeries and the strategies for wide adoption of such technologies, which partially motivated the documentation of this protocol.
The authors declare no competing interests.
Peer review information Nature Protocols thanks Jasmin Hefendehl and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Key references using this protocol
Ghanbari, L. et al. Sci. Rep. 9, 1023 (2019): https://doi.org/10.1038/s41598-018-37073-w
Ghanbari, L. et al. Nat. Commun. 10, 1500 (2019): https://doi.org/10.1038/s41467-019-09488-0
Video demonstrating the use of the Craniobot to perform a 3-mm-diameter circular craniotomy centered at 2 mm to the right of and 2 mm posterior to Bregma.
Setup file for installing and using the Craniobot control software.
Setup file for installing and using the Arduino microcontroller.
A compressed file archive consisting of all computer-aided design (CAD) files of custom-fabricated components needed for assembly of the Craniobot and the surface profiler.
A file containing the code for the microcontroller to regulate the switching circuit.
A compressed file archive consisting of .csv files for performing craniotomy over the whole dorsal cortex and a rectangular craniotomy.
A compressed file archive consisting of all CAD files required for assembly of the See-Shell implant.
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Rynes, M.L., Ghanbari, L., Schulman, D.S. et al. Assembly and operation of an open-source, computer numerical controlled (CNC) robot for performing cranial microsurgical procedures. Nat Protoc 15, 1992–2023 (2020). https://doi.org/10.1038/s41596-020-0318-4