Recording central nervous system responses of freely-swimming marine and freshwater fishes with a customizable, implantable AC differential amplifier

Abstract

Background: Fish have adapted to a diversity of environments but the neural mechanisms underlying natural aquatic behaviors are not well known. New method: We have developed a small, customizable AC differential amplifier and surgical procedures for recording multi-unit extracellular signals in the CNS of marine and freshwater fishes. Results: Our minimally invasive amplifier allowed fish to orient to flow and respond to hydrodynamic and visual stimuli. We recorded activity in the cerebellum and optic tectum during these behaviors. Comparison with existing methods: Our system is very low-cost, hydrodynamically streamlined, and capable of high-gain in order to allow for recordings from freely behaving, fast fishes in complex fluid environments. Conclusions: Our tethered approach allows access to record neural activity in a diversity of adult fishes in the lab, but can also be modified for data logging in the field.