StereoPylot: An Open-Source Raspberry Pi-Based Stereotaxic Apparatus Controller with 3D Printed Components for Fully Motorized Control, Digital Display, and Customizable Features.

Stereotaxic surgery is a powerful technique used to deliver drugs, viral vectors, and/or probes into discrete regions of the brain. Over the past decade, the emphasis on performing complex surgeries for neural circuit manipulations or studying multiple brain regions in the same animal has increased. While analog stereotaxic instruments are generally suitable for these types of experiments, the surgeon must accurately read vernier scales for each brain region of interest, which is both time-consuming and prone to user error. Although vendors now offer digital stereotaxic instruments that overcome the limitations of analog instruments, digital units are cost-prohibitive and often come in limited configurations that lack clear paths to customize or upgrade as experimental needs change. To overcome these issues, we've created StereoPylot, an open-source Raspberry Pi-based stereotaxic controller with 3D-printed components. StereoPylot features motorized control of X-, Y-, and Z-axes, variable motor speed, programmable buttons, and a digital display for stereotaxic coordinates. We also created a custom graphical user interface which allows surgeons to move the manipulators to an area of interest by manually entering stereotaxic coordinates on screen or by loading a preset file that contains a list of user-defined stereotaxic coordinates. We demonstrate practical application of StereoPylot by quantifying viral expression in three male and three female Long-Evans rats and provide instrument accuracy and precision measurements. StereoPylot is therefore feature-rich and highly customizable while being relatively inexpensive to implement onto existing analog instruments commonly found in neuroscience laboratories.