Figure 1.

Summary of experimental paradigm, behavioral performance, and recording field

(A) Schematic spectrogram of an example SFG stimulus. Figure elements are shown in red, and random ground elements in black. Line plots below indicate the 900-ms-long behavioral response window for the displayed stimulus as well as the behavioral outcome for touch bar release inside (HI, hit) and outside (MI, miss) of this time window.

(B) Example control stimulus without figure. The trial was correctly performed, if no touch bar release occurred until sound presentation finished (CR, correct rejection). Otherwise, the trial was counted as false alarm (FA).

(C–E) Behavioral detection performance of monkey 1 (M1; left, sessions: n = 87) and monkey 2 (M2; right, sessions: n = 67) for coherence levels of 8 (Coh8; green) and 12 (Coh12; red) elements, respectively. Only sessions with more than 200 trials were included. (C) Average d-prime values. (D) Mean reaction time. (E) Response variability measured by the coefficient of variation (standard deviation divided by mean). Stars indicate significance (two-sided Wilcoxon rank-sum test): ^∗∗p < 0.01, ^∗∗∗p < 0.001.

(F) Structural T2 MRI of both subjects. Green vertical lines indicate location of interaural line. Distance of coronal sections from interaural line (mm) is indicated below slice. Recording chamber is filled with saline for visibility. Both recording chambers have a medial tilt (M1: 10 deg, M2: 15 deg) to allow easier access to the lateral auditory cortex. Auditory cortex is highlighted in red. A 10-mm scale bar is shown below.

(G) Best frequency maps for M1 (top) and M2 (bottom). Color code indicates average best frequency across the surface of the superior temporal gyrus. Only sites with significant pure tone tuning are shown. Recording coordinates with unmodulated frequency response are not included. Y coordinates show distance to the interaural line (IAL). X coordinates show the grid position. Maps are smoothed with a 2 × 2-mm Gaussian kernel. The black line indicates the division boundary between anterior and posterior recording field based on low-frequency gradient reversal. Labels illustrate the estimated areal membership.

(H) Latency map for M1 (top) and M2 (bottom). Color code illustrates average peak latency for each grid position.

(I) Location of channels that exhibit significant LFP phase locking (red triangles) overlaid on M2's best frequency map. Strength of phase locking (no. of click train frequencies that elicit phase locking response) is indicated by transparency of triangle. See also Figures S1 and S2.