Abstract
1. Effects of static pressure changes on sound reception were studied withneurophysiological techniques in goldfish. Static pressure changes were appliedon the fish's abdomen in order to make the saccular otolith deviate from itsnormal position.
2. Microphonic potentials as recorded with microelectrodes from the saccularmacula were evoked at twice the frequency of the sound. When the pressureon the abdomen was increased, peaks of the microphonic that corresponded tothe compression phase of the sound were augmented and those which corre-sponded to the rarefaction phase were suppressed. The effect of a decreaseof the pressure took place in an opposite direction.
3. Action potentials were recorded intracellularly from single saccular nervefibers. Effects of pressure changes on the activity of these fibers were different depending on the direction of the pressure change and on the response typeof individual nerve fibers.
4. One type of fiber responded with graded depolarization only to an increaseof the pressure but did not respond to its decrease. When sound stimulus wasapplied with pressure changes, response of the fiber to sound stimulus wasfacilitated during a rise of the pressure, but it was suppressed during a pressuredecrease. There were also fibers that responded only to a decrease of thepressure. Behavior of these fibers was just the opposite to that describedabove.
5. The other type of fibers responded to both an increase and a decrease ofthe pressure. They correspond to fibers that set up discharges at a rate twicethe frequency of the sound. In this type of fibers, responses to the compression phase of the sound were facilitated and responses to the rarefactionphase were suppressed during a rise of the pressure. A decrease of the pressure produced an opposite effect.
6. Mechanisms of interaction between pressure changes and sound stimuliwere discussed.
