Faculty of Fisheries, Kagoshima University, Shimoarata, Kagoshima 890-0056, Japan
Afferent nerve activities of the posterior lateral line in response to sinusoidal dipole stimuli and self-generated stimuli caused by swimming motion were studied. The threshold sensitivity curves in terms of velocity and acceleration indicated that the lateral line of carp has high sensitivity below 200 Hz, suggesting that lateral line response properties are like a low-pass filter. The trunk motions, body bending toward and against the sides of nerve recordings, stimulated the lateral line. The peak of the lateral line nerve responses was obtained almost simultaneous with the increase of velocity and acceleration components of the motions rather than lateral displacement of the trunk. Regression analyses revealed that the intensities of the lateral line responses correlated well with the peak velocities and accelerations. This study is the first demonstration of the relationships between the magnitudes of self-motion and lateral line responses.