Abstract
In order to analyze informations in a train of nerve impulses evoked by the external stimuli on the sensory receptor, an electrical device for counting impulse trains was designed. The device consists of the following three major parts.
1) An electronic counter consisting of a counting unit and a D-A converter. Frequency characteristics of the counter is linear from 0 to 4096 pulses/sec and input-output characteristics of the D-A converter is perfectly linear over the full range. When nerve impulses are passed through a slicer which eliminates noise and unwanted signals, the output signal from the slicer triggers a one-shot multivibrator which subsequently generates rectangular pulses. The rectangular pulses are then fed to the counter, which displays frequencies of nerve impulses on a pen-writing recorder.
2) A time interval-display unit consisting of a sawtooth wave form generator triggered by rectangular pulses into which nerve impulses have been converted. After receiving a nerve impulse, a linear time base generator is reset and restarted. The generator produces sawtooth wave forms, V (t1) = A (t2-t1), V (t2) =A (t3-t2), …… for a train of nerve impulses arriving at times t1, t2, t3, ……. Intervals of successive nerve impulses can be shown as the final value of each sawtooth wave form and recorded on a pen-writing recorder.
3) An integrating unit which is used to indicate the response magnitude of compound action potentials in the whole nerve. The response magnitude is presented by the successive integrated value of compound action potentials per unit time, which can be varied from 50 msec to 20 sec.
The device is completely transistorized, compact and portable, and it is considered to be satisfactory for use as a nerve impulse counting device for analyzing data obtained by physiological experiments or as a monitor on line during the course of an experiment.
