Reconfigurable 3D-Printed headplates for reproducible and rapid implantation of EEG, EMG and depth electrodes in mice.

ABSTRACT

BACKGROUND: Mouse models are beneficial to understanding neural networks given a wide array of transgenic mice and cell-selective techniques. However, instrumentation of mice for neurophysiological studies is difficult. Often surgery is prolonged with experimental error arising from non-concurrent and variable implantations. NEW METHOD: We describe a method for the rapid, reproducible and customizable instrumentation of mice. We constructed a headplate that conforms to the mouse skull surface using script-based computer aided design. This headplate was then modified to enable the friction-fit assembly prior to surgery and printed with a high-resolution resin-based 3D printer. Using this approach, we describe an easily customized headplate with dural screws for electrocorticography (ECoG), electromyogram (EMG) electrodes, cannula hole and two microdrives for local field potential (LFP) electrodes. RESULTS: Implantation of the headplate reliably takes less than 40 min, enabling a cohort of eight mice to be implanted in one day. Good quality recordings were obtained after surgical recovery and the headplate was stable for at least four weeks. LFP electrode placement was found to be accurate. COMPARISON WITH EXISTING METHODS: While similar approaches with microelectrodes have been used in rats before, and related approaches exist for targeting one brain region with tetrodes, we do not know of similar head-plates for mice, nor a strictly source-code and easily reconfigurable approach. CONCLUSIONS: 3D printing and friction-fit pre-assembly of mouse headplates offers a rapid, easily reconfigurable, consistent, and cost-effective way to implant larger numbers of mice in a highly reproducible way, reducing surgical time and mitigating experimental error.