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A Technique for Discriminating Direction of Propagation of Action Potentials Recorded from an Intact Mixed Nerve
1 Zoology Department, Makerere College Uganda; Zoology Department, University of California, Berkeley, California, U.S.A.
1. Activity is recorded in the nerve by two external electrodes spaced a known distance apart. Action potentials trigger 10 µsec. pulses in each channel. Those of one channel generate, after a variable delay, selector pulses which gate the output from the other channel, and this is applied to an electronic counter or other display.
2. As action potentials conduct at finite velocity, gate and delay times can be set to accept and count only impulses of a given range of conduction velocities propagating from the selector electrode to the counter electrode.
3. Reversal of input connexions allows discrimination of impulse traffic moving in the reverse direction. This is best done from a magnetic tape recording of the same activity; the recorder for this purpose must meet stringent requirements.
4. Simultaneous signals at both electrodes are rejected, distinguishing between action potentials and other potential changes, and thus allows retrieval of low amplitude nervous activity from recorded noise.
5. Other applications include selection of impulses of a given amplitude or conduction velocity, and the measurement of conduction velocities of a population of different nerve impulses.
Submitted on January 3, 1969
