 A bubble of air trapped in the polyethylene tubing which contains the probe adds buoyancy and makes the electrode the same density as the nerve in which it is implanted, thereby allowing the two to move together.A section of paraffin is used to connect the electrode to a handle which is used only during the implantation process, then removed.Nerve impulses detected by the microelectrodes are fed into a preamplifier directly attached to the frog's jaw, and passed on to a post-data amplifier for spacecraft telemetry.