Fig. 6. Response patterns to a metal object located at different distances lateral to the fish's body. Top: primary afferent unit response as a function of the rostro-caudal position and lateral distance of the object. Two groups of 10 raster diagrams represent the latency of the spikes of a primary afferent unit when an object was moved in 5 mm steps rostro-caudally along the fish body, at distances of 2 mm (left) and 7 mm (right) from the skin. The vertical red lines indicate the mean latencies of the basal spike discharges in the absence of an object. Bottom: color maps represent the field potential equivalent to the sensory response (FPSR) as a function of time and object position as in Fig. 5, for objects moved rostro-cadally along the fish's body axis, at lateral distances of 1 mm (left), 7 mm (middle) and 17 mm (right) from the skin. Object position is shown relative to the fish picture on the left; the red dot indicates the receptive field center.