Fig. 8. Effect of CNQX on transition state ITD tuning in the ICX. The units were from owls with 30–154 d of prism experience.A, Effect of increasing ejection currents of CNQX (increasing square size, 4, 5, and 10 nA, respectively) at a representative site. Vertical line, Normal best ITD for the transect. The effect of AP-5 (increasing closed circle size, 10, 25, and 40 nA, respectively) at this same site is shown below for comparison (same site shown in Fig. 5A).Bottom panel, Blockade produced by the median ejection currents of CNQX (squares) and AP-5 (circles and regression line) as a function of ITD. AP-5, R2 = 0.705 andp = 0.0008; CNQX, no significant regression (p = 0.80). B, Another example. Vertical line, Normal ITD for the transect (R10 μsec). AP-5, R2 = 0.946 andp < 0.0001; CNQX, no significant regression (p = 0.37). C, Response blockade produced by CNQX for normal and learned responses for all sites with transition state ITD tuning. Gray region, Normal range of blockade asymmetry observed with CNQX in normal owls, calculated as the mean ± 2 SD of the difference between the response blockade on the two flanks of the ITD tuning curve (from CNQX data in Fig. 3D); squares withX, sites showing significant AP-5 asymmetry;filled square, the single asymmetric effect of CNQX.