ELECTRIC RESPONSES TO ACOUSTIC STIMULI IN THE DECEREBRATE ANIMAL

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Abstract
Although the decerebrate cat rarely shows motor response to acoustic stimuli, electric responses to these stimuli may be regularly recorded from the medulla oblongata or the brain stem by means of a string galvanometer and electron-tube amplifier. With a sound of brief duration, the response is usually more abrupt and often larger than the response to a maximal induction shock applied to the sciatic nerve. When tuning forks were used as stimuli, the electric response showed only feeble oscillations correlated with a frequency of 104 d.v. per sec. With higher frequencies little or no correlated response could be found. By holding a card in contact with a revolving cogwheel a stimulus of variable frequency was obtained. In this case the record revealed oscillations correlated with the contacts of the card with the cogs up to a frequency of 220 per sec. The relative merits of the place-theory and the frequency-theory of pitch discrimination are discussed in the light of the all-or-none law of nerve conduction. The duration of the refractory phase of nerve renders the frequency-theory highly improbable. The observation of a nerve-impulse frequency correlated with that of the sound waves up to more than 200 per sec. is equally compatible with either.

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