Information Transmission in the Auditory Brainstem Figure 11. Normalized SACs and harmonic distortion of VCN neurons’ responses to /e/. Panels in A, C and E contain normalized SACs constructed from high-sync neurons (thin lines) and Group 3 neurons (red thick lines) responses to /e/. High-sync neurons in A, C and E are the same neurons whose histograms are shown in Figs. 10A–10C, respectively. Group 3 neurons in panel A, C and E are the same as in Figs. 10–10C. Panel B displays a scatter plot of CIs as a function of CF for high-sync (filled triangles, N = 13), Group 2 (open triangles, N = 6) and Group 3 VCN neurons (inverted triangles, N = 13). Panel C displays THDs for the same neurons in panel B. doi:10.1371/journal.pone.0044286.g011 in Figs. 12B and 12D, respectively. The dot raster plot of the high- sync neuron’s responses consists of a series of vertical lines occurring at approximately 2.5 ms intervals (or multiples of this number), as easily appreciated in the three lines occurring between 95 and 100 ms (Fig. 12B). This contrasts with the apparently random nature of the ANF responses (Fig. 12D). SACs computed from the responses of those units are shown in Fig. 12C. Both SACs in Fig. 12C consist of a damped oscillation whose periodicities are approximately equal to the inverse of each of the fiber’s CF. Individual peaks in the high-sync neuron’s SAC (thin line in Fig. 12C) are narrower and have higher values than peaks in the ANF’s SAC (red thick line in Fig. 12C). SACs constructed from the responses to /i/ of two other fibers with higher CFs (around 900 Hz) are shown in Fig. 12E. Although the overall shape of both SACs resembles those in Fig. 12C, the oscillation’s periodicity varies in proportion to the fiber’s CF. Temporal resolution in SACs of high-sync neurons is higher, as indicated by the narrower and higher individual peaks, than in SACs of ANFs. A similar enhancement in temporal features was also obtained from the responses to broadband noise of high-sync PLOS ONE | www.plosone.org 15 September 2012 | Volume 7 | Issue 9 | e44286