Free-running activity rhythms of nine green finches (Carduelis chloris) were stud ied under the influence of a 10-Hz square-wave electrical field. With a field strength of |E| = 2.5 V/m in the empty cage, the population had a mean period of 23.64 ± 0.77 hr. In the same experiment, but without the electrical field, the period was 23.66 ± 0.80 hr. These results are in contradiction to Wever's description of a field-induced shortening of the period. A series of experiments with 10-Hz pulses of the same square-wave form, yet with various field strengths (8.7 and 65.2 V/m), also gave no effects.
References
1.
Bach, W., and S. Lang (1976) Messung niederfrequenter elektrischer Felder mit einer halbleiterbestückten Elektrometersonde. Biomed. Tech.21: 185-188.
2.
Eskin, A. (1971) Some properties of the system controlling the circadian activity rhythm of sparrows. In Biochronometry, M. Menaker, ed., pp. 55-80, National Academy of Sciences, Washington, DC.
3.
Ehret, P.F., and C.H. Duffy (1983) High-strength 60-Hz electric fields are circadian zeitgebers in mice. Chronobiologia10: 124-124.
4.
Pfützner, H. (1979) The standardization of experimental investigations of biological effects of low frequency electric and magnetic fields. Int. J. Biometeor.23: 271-278.
5.
Schaefer, H. (1983) Über die Wirkung elektrischer Felder auf den Menschen. Sitzungsberichte der Heidelberger Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, 3, Abhandlung, pp. 1-110, Springer-Verlag , Berlin.
6.
Wever, R. (1968a) Einfluß schwacher elektromagnetischer Felder auf die circadiane Periodik des Menschen. Naturwissenschaften55: 29-32.
7.
Wever, R. (1968b) Gesetzmäßigkeiten der circadianen Periodik des Menschen, geprüft an der Wirkung eines schwachen elektrischen Wechselfeldes . Pflügers Arch.302: 97-122.
8.
Wever, R. (1973) Human circadian rhythms under the influence of weak electric fields and the different aspects of these studies. Int. J. Biometeor.17: 227-232.
9.
Wever, R. (1985) The electromagnetic environment and the circadian rhythms of human subjects. In Biological Effects and Dosimetry of Static and ELF Electromagnetic Fields, M. Grandolfo, S. M. Michaelson, and A. Rindi, eds., pp. 477-523, Plenum, New York .
10.
Wirz-Justice, A., G.A. Groos, and T.A. Wehr (1982) The neuropharmacology of circadian timekeeping in mammals. In Vertebrate Circadian Systems, J. Aschoff, S. Daan, and G. A. Groos, eds., pp. 183-193, Springer-Verlag , Berlin.
