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Measurement of current spread from microelectrodes when stimulating within the nervous system

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Summary

Tungsten stimulating microelectrodes have been tested in monopolar, bipolar and concentric configurations for the extent to which unwanted current spread occurred. Current spread from monopolar electrodes in close conformity with the predictions of the inverse square law, both in vitro and in vivo. The bipolar and concentric configurations, tested only in vitro, had current-spread characteristics which did not follow the inverse square law so closely. The bipolar configuration gave little reduction in spread, compared with a monopolar electrode, but the concentric configuration did reduce the extent of stimulus spread. The extent of spread depends greatly upon a number of experimental variables, including the dimensions of the microelectrode tip. For studies requiring precise localization, with low stimulus currents, it is advisable to determine the inverse square law constant for each experimental situation. For more generalized stimulation purposes within the mammalian C.N.S., employing monopolar microelectrodes of moderate tip size, brief pulses of 10 μA can be expected to stimulate myelinated axons within about 0.15 mm of the tip, and 100 μA will stimulate within a radius of about 0.5 mm.

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References

  1. Andersen, P., Hagan, P.J., Phillips, C.G., Powell, T.P.S.: Mapping by microstimulation of over-lapping projections from area 4 to motor units of the baboon's hand, Proc. roy. Soc. B 188, 31–60 (1975)

  2. Asanuma, H., Sakata, H.: Functional organization of a cortical efferent system examined with focal depth stimulation in cats. J. Neurophysiol. 30, 35–54 (1967)

  3. Evans, M.H.: Measuring small rapid changes in nerve threshold during exposure to snake venom. Nature (Lond.) 200, 368 (1963)

  4. Hubel, D.H.: Tungsten microelectrode for recording from single units. Science 125, 549–550 (1957)

  5. Jankowska, E., Roberts, W.J.: An electrophysiological demonstration of the axonal projections of single spinal interneurones in the cat. J. Physiol. (Lond.) 222, 597–622 (1972)

  6. Merrill, E.G., Ainsworth, A.: Glass-coated platinum-plated tungsten microelectrodes. Med. biol. Engng 10, 662–672 (1972)

  7. Olds, J.: Self-stimulation of the brain. Science 127, 315–324 (1958)

  8. Stark, P., Fazio, G., Boyd, E.S.: Monopolar and bipolar stimulation of the brain. Amer. J. Physiol. 203, 371–373 (1962)

  9. Stoney, S.D., Thompson, W.D., Asanuma, H.: Excitation of pyramidal tract cells by intracortical microstimulation: effective extent of stimulating current. J. Neurophysiol. 31, 659–669 (1968)

  10. Valenstein, E.S., Beer, B.: Unipolar and bipolar electrodes in self-stimulation experiments. Amer. J. Physiol. 201, 1181–1186 (1961)

  11. Wise, R.A.: Spread of current from monopolar stimulation of the lateral hypothalamus. Amer. J. Physiol. 223, 545–548 (1972)

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The work was all done while E.V.B. was on Industrial Training leave from the North-East Polytechnic, Romford Road, London E. 15

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Bagshaw, E.V., Evans, M.H. Measurement of current spread from microelectrodes when stimulating within the nervous system. Exp Brain Res 25, 391–400 (1976). https://doi.org/10.1007/BF00241729

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Key words

  • Current spread
  • Microelectrodes
  • Stimulus spread