AN ANALYSIS OF MICROPHONIC POTENTIALS OF THE SACCULUS OF GOLDFISH

1. A study was made to clarify the nature of the intramacular microphonic potentials of the sacculus of goldfish in comparison with the more common, negative microphonic potential which can be recorded from the saccular lumen. The intramacular microphonic potential was evoked as mostly positive deflections and at the same frequency as sound, while negative microphonic potential was evoked at twice the frequency of the sound. 2. A comparison was made of different types of microphonic potentials obtained from various depths of the macula. Effects of pressure changes applied to the fish's abdomen were also studied. 3. Studies on input-output function disclosed that the intramacular microphonic potential was sinusoidal in shape for a weak sound, but it deviated from sinusoidal when sound intensity increased, for its negative deflections were clipped. It was found that the negative microphonic potential could be recorded only for such a relatively strong sound. 4. From these results, it was concluded that the intramacular microphonic potential represents the activity of hair cells of a homogeneous group. The operational characteristics of hair cell activity were drawn based on results of input-output studies. 5. The recording conditions of intramacular microphonic potentials are discussed in relation to the functional differentiation of the saccular macula whose dorsal and ventral halves are concerned only with the reception of compression and rarefaction phases of sound, respectively.