An implantable two axis micromanipulator made with a 3D printer for recording neural activity in free-swimming fish

Background Chronically implanted electrodes allow monitoring neural activity from free moving animals. While a wide variety of implanted headstages, microdrives and electrodes exist for terrestrial animals, few have been developed for use with aquatic animals. New method A two axis micromanipulator was fabricated with a Formlabs 3D printer for implanting electrodes into free-swimming oyster toadfish (Opsanus tau). The five piece manipulator consisted of a base, body, electrode holder, manual screw drive and locking nut. The manipulator measured approximately 25 × 20 × 30 mm (l × w × h) and weighed 5.28 g after hand assembly. Results Microwire electrodes were inserted successfully with the manipulator to record high fidelity signals from the anterior lateral line nerve of the toadfish. Comparison with existing method(s) The micromanipulator allowed the chronically implanted electrodes to be repositioned numerous times to record from multiple sites and extended successful recording time in the toadfish by several days. Conclusions Three dimensional printing allowed an inexpensive (< $US 5 material), two axis micromanipulator to be printed relatively rapidly (<2 h) to successfully record from multiple sites in the anterior lateral line nerve of free-swimming toadfish.