Fig. 4. Lateral extent of main response areas of 48 midbrain lateral line units, including all TS2 units (above the horizontal line) and 13 TS1 units (below the horizontal line). The main response area of a unit is the sum of the sphere positions that elicited the first well-defined bursts (see text) from that unit, pooled for both sphere-run directions. Black, green and violet colours indicate rostral, intermediate and caudal response areas, respectively. As indicated in the enlarged brain drawing using the same colour code, units were recorded in the anterio-lateral (black), medio-lateral (green) and posterior-lateral (violet) TS.