Responses to dipole stimuli of anterior lateral line nerve fibres in goldfish, Carassius auratus, under still and running water conditions

We investigated how fibres in the anterior lateral line nerve of goldfish, Carassius auratus, respond to sinusoidal water motions in a background of still or running water. Two types of fibres were distinguished: type I fibres, which most likely innervate superficial neuromasts, were stimulated by running water (10 cm s-¹) while type II fibres, which most likely innervate canal neuromasts, were not stimulated by running water. The responses of type I fibres to sinusoidal water motions were masked in running water whereas responses of type II fibres were not masked. These findings are in agreement with previous data obtained from the posterior lateral line nerve of goldfish. Furthermore, we demonstrate here that for type I fibres the degree of response masking increased with increasing flow velocity. Finally, the ratio between responses that were masked in running water (type I) and those that were not masked (type II) increases with increasing flow velocity. Flow fluctuations that were generated by a cylinder in front of the fish did not affect ongoing activity in the flow, nor the dipole-evoked responses. The findings are discussed with respect to particle image velocimetry data of the water motions generated in the experiments.