RESPONSES OF THE GOLDFISH TRUNK LATERAL-LINE TO MOVING-OBJECTS

We recorded the responses of single afferent fibers in the posterior l ateral-line nerve of the goldfish, Carassius auratus, to a small objec t moving in the water. Responses consisted of a dominant and reproduci ble pattern of discharge which was characterized by excitation followe d by inhibition or vice versa. The pattern depended on the direction i n which the object moved and was inverse when the direction was revers ed. About half of the fibers continued to discharge bursts of spikes f or a long time after the object had passed the fish. These spike burst s were not reproducible from one stimulus presentation to the next. In many fibers, the pattern of the response changed with speed and later al distance of the moving object. Response strength increased with inc reasing object speed and decreasing lateral distance. Measurements of water motions revealed that the object generated complex water movemen ts, aspects of which were reflected in the discharges of primary later al-line afferents. The observed uniformity of the responses in the per iphery suggests that many, but not all, of the response patterns of ce ntral lateral-line units to moving objects are due to additional infor mation processing by the central nervous system and not to peripheral hydrodynamic effects.