1. Department of Animal Physiology, Faculty of Agriculture, Nagoya University, Furo-cho, Chikusaku, Nagoya-shi, Aichi 464, Japan.
2. Case Western Reserve University, School of Medicine, Cleveland, OH 44106.
3. Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60201.
4. Institute of Neuroscience, University of Oregon, Eugene, OR 97403.