Fig. 2.

DRFs for 2 delay-sensitive units and cortical distribution of best delay. A and B: responses of 2 delay-sensitive units from the rostral (A) and caudal (B) part of the posterior dorsal field in the AC. The spike count in both DRFs is normalized and coded in grayscale; the black dotted contour line represents the response threshold at 50% of the unit’s maximal spike rate. The echo delay/echo level combination eliciting the maximal response is marked by an asterisk (best delay, BD). The echo delay with the lowest threshold (characteristic delay, CD) is marked by a circle. BDs were 8.0 (A) and 20.0 ms (B), and CDs were 9.5 (A) and 20.0 ms (B). C: BDs of all recorded delay-sensitive units projected on the flattened surface of the AC. The position of each unit is marked by circles; the BD is coded in grayscale. The outlines of the AC are indicated by dashed lines and the borders of the 4 subfields by solid lines. AC outlines and subfields are according to Hoffmann et al. (2008). ADF, anterior dorsal field; AVF, anterior ventral field; PVF, posterior ventral field; PDF, posterior dorsal field.