Some Possible Limits on the Minimum Electrical Signals of Biological Significance
It is of interest to consider what might be the lowest-level electric and magnetic signals that are biologically important. This is important in helping to decide what experiments are worth performing, as well as in setting safety standards. Deciding what the lowest-level fields or currents are is not a simple issue, because the biological effects of an externally applied electric field or current may be dependent on the particular cell or organ to which they are applied as well as on the time of their application. The amplitude of the current, the field direction, the pulse length, the frequency and the shape of the signal may all be important when the system is nonlinear or time-dependent. Thus two current pulses of the same size and shape may have quite different effects on the firing rate of a pace-maker cell, depending on the point of the firing cycle at which they are injected or on the closeness of the repetition rate to the natural firing rate. In addition, we can reasonably expect that the minimum signal for which we can detect a biological change will decrease as our measuring techniques improve, and as our biological understanding improves.
KeywordsFiring Rate Noise Voltage Squid Axon Mylar Film Minimum Signal Level
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- 1.A. Yariv, “Optical Electronics”, third edition, 1985. New York: olt Rinehart Winston.Google Scholar
- 2.F.N. Hooge, “1/f Noise”, Physica 83B (1976), pp. 14–23.Google Scholar
- 3.M.S. Keshner, “1/f Noise”, Proc. IEEE 70, No. 3, (March 1982), pp. 212–218.Google Scholar
- 7.M. Ten Hoopen and A.A. Verveen, “Nerve-Model Experiments on Fluctuation in Excitability,” in Nerve, Brain and Memory Models, ed. N. Wiener and J.P. Schade (Progress in Brain Research, Vol. 2). New York: Elsevier, 1963, pp, 8–21.Google Scholar
- 8.E. Siebenga, A. Meyer, A.A. Verveen, “Membrane Shot Noise in Electrically Depolarized Nodes of Ranvier,” Pflüger Arch 341, pp. 87–96.Google Scholar
- 9.E. Smith, “The Natural Radio Noise Source Environment,” IEEE EMC Symp., Sept. 1982.Google Scholar
- 12.“Nonlinear Microwave Bioeffects on Isolated Neurons of Aplysia,” M.S. thesis by Joseph D. Forster, University of Colorado, Boulder, Department of Electrical Engineering, 1981.Google Scholar
- 13.“Nerve-Model Experiments on Fluctuation in Excitability,” M. Ten Hoopen and A.A. Verveen in Nerve, Brain and Memory Models, ed. N. Wiener and J.P. Schade (Progress in Brain Research, Vol. 2). New York: Elsevier, 1963, pp. 8-21.Google Scholar
- 14.H. Wachtel, “Firing-pattern changes and transmembrane currents produced by extremely low frequency fields in pacemaker neurons, in Proc. 18th Annu. Hanford Life Sci. Symp., Technical Information Center, Department of Energy, Richland, Wash., 1978, p. 132.Google Scholar