Frequency response of the lateral-line organ of xenopus laevis

Abstract

The stimulus response relation of the epidermal lateral-line organ of Xenopus laevis was studied by recording activity of single afferent nerve fibres in isolated preparations. Linear frequency response analysis over a frequency range of 0.1--100Hz was performed under steady-state conditions, using small amplitude, sinusoidal water displacements produced by a glass sphere at a short distance from the skin. Period histograms of afferent nerve activity were computed, and amplitude, phase and mean activity of the response were determined by means of Fourier analysis. A standardization procedure at the start of each experiment made scaling of the frequency responses of different preparations unnecessary. The results show that for small stimulus amplitudes the response of the lateral-line organ over the whole range of frequencies studied can adequately be described as a modulation of the spontaneous activity. The amplitude of the response is proportional to the stimulus amplitude, and the phase of the response is independent of stimulus amplitude. The lateral-line organ of Xenopus laevis can thus be regarded as a linear system for stimuli which produce modulation of the spontaneous activity. The frequency response demonstrates unequivocally that the lateral-line organ of Xenopus laevis functions as a water velocity detector. For frequencies of stimulation from 0.1--20Hz the gain increases with a slope of 7.5 dB/oct, and up to 5Hz the response is almost in phase with the water velocity. The extent to which the different transmission steps between stimulus and response will contribute to the frequency response is discussed.

CFD study of hydrodynamic signal perception by fish using the lateral line system

“…However, knowing the frequencies used, a wall strain rate threshold range of S wall = 0.07 − 0.25 s −1 at 10 Hz, S wall = 0.44 − 1.4 s −1 at 50 Hz, up to a range of S wall = 0.7 − 4.0 s −1 at 100 Hz, can be determined using equation 7. Kroese et al (1978) used a sphere of radius a=1.55 mm, oscillating at f=20 Hz parallel to the fish surface, with a displacement amplitude of A=4 µm, and placed at a distance of r =3.75 mm from the surface. They assumed a hair cell height of 100 µm, which is fully immersed in the boundary layer flow.…”

“…an oscillating sphere stimulus), the use of these threshold definitions can help to resolve it. From the data presented in three neurophysiological experiments, either the velocity threshold and approximate strain rate threshold (Dinklo, 2005), or the wall strain rate threshold (Coombs and Janssen, 1990), or both (Kroese et al, 1978), could be extracted and used as limited benchmarks for further comparisons.…”

“…The (Kroese et al, 1978), it is unlikely that they are strong enough to account for this difference (numerical simulation showed gains of 4 times).…”

“…This should be an area of future investigation. Kroese et al, 1978 surface neuromast height ( Figure 4-16: The boundary layer flow (solid line) due to an oscillating sphere next to fish surface is calculated using equation 4.8. Potential flow theory (such as used by Kroese et al (1978) does not account for reduced velocities that affect the superficial neuromast when it lies within the boundary layer.…”

“…Kroese et al (1978) determined the superficial neuromasts of the Xenopus Laevis to have a velocity detection threshold of 38 µm/s . They used potential flow theory for an oscillating sphere next to a wall to calculate the hair displacement, but did not take into account the effects of the boundary layer.…”