1. Acknowledgments. This work was supported by the Norwegian Research Council for Science and the Humanities, by a NATO Science Fellowship (J.-C.L.) from the Natural Sciences and Engineering Research Council of Canada and by a Fellowship (G.-Y.H.) from the Norwegian Development Agency — NORAD.
2. Lømo, T., Acta physiol. scand., Suppl.277 (1966) 128.
3. Bliss, T. V. P., and Lømo, T., J. Physiol., Lond.232 (1973) 331.
4. Swanson, L. W., Teyler, T. J., and Thompson, R. F., Neurosci. Res. Prog. Bull.20 (1982) 611.
5. Berger, T. W., Science223 (1984) 627.