A new technique for implanting a fine-wire microelectrode for chronic recording of unit activity from freely-moving mice

We report here a newly developed chronic implantation technique using an ep oxy-coated fine-stainless steel wire (33 mu m in diameter) to record single unit activity from the brain of freely-moving mice with as little tissue i njury as possible. Since the fine-wire electrode is not capable of staying straight by itself or of penetrating into the brain, a pair of permanent ne odymium magnets placed on a micromanipulator as well as below the animal's head was used for stereotaxic implantation to keep the fine-wire straight a nd strong by the magnetic fields. With those implanted electrodes recording of single units from the hippocampal CAI of freely-moving mice was perform ed during sleep and wakefulness. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.