Automated placement of stereotactic injections using a laser scan of the skull

Stereotactic targeting is a commonly used technique for performing injections in the brains of mice and other animals. The most common method for targeting stereoscopic injections uses the skull indentations bregma and lambda as reference points and is limited in its precision by factors such as skull curvature and individual variation, as well as an incomplete correspondence between skull landmarks and brain locations. In this software tool, a 3D laser scan of the mouse skull is taken in vitro and registered onto a reference skull using a point cloud matching algorithm, and the parameters of the transformation are used to position a glass pipette to place tracer injections. The software was capable of registering sample skulls with less than 100 micron error, and was able to target an injection in a mouse with error of roughly 500 microns. These results indicate that using skull scan registration has the potential to be widely applicable in automating stereotactic targeting of tracer injections. Introduction Many techniques in modern experimental neuroscience involve performing procedures such as stimulation, electroporation, or injection on fine structures in the brain during surgery on a live animal. The most common technique for performing these procedures is stereotactic surgery. During stereotactic surgery, the animal is fixed in a stereotactic apparatus, the surface of the skull is exposed, and features of the skull are used to determine where to inject to reach a target brain location. Fixing the skull within the stereotactic frame places the brain within an arbitrary three-dimensional coordinate system, and the assumption is then made that this coordinate system corresponds to a reference atlas of the brain which can be used to target injections. One important application of stereotactic surgery is in performing injections of tracer and other compounds for brain mapping. The Mouse Brain Architecture project is one such application, which makes use of stereotactic injections of tracers to map the connections between known areas of the mouse peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission. The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/010603 doi: bioRxiv preprint first posted online Oct. 22, 2014;