Tonotopic organization of MGBv and MGBm. A, Examples of nonmonotonic BF functions across the lateral-to-medial depth within MGB obtained from rostral, intermediate, and caudal positions. The high-frequency reversal was used to divide MGBv (diamond to square) from MGBm (square to triangle) recording sites. Dashed lines represent linear fits of MGBv and MGBm BF functions used to calculate BF slope (D). B, BF measurements across the rostral-to-caudal extent of the lateral wall of MGBv. Dashed line represents linear fit. C, BF changes across the lateral-to-medial extent of MGBv (gray circles) and MGBm (black squares). Dashed lines indicate linear fits applied to BF shift data from MGBv (gray) or MGBm (black). D, Slope of BF changes across the rostral-to-caudal extent of the MGB. Positive values indicate increasing BF functions; negative values indicate decreasing BF functions. E, Mean ± SEM FRA bandwidth measured 10 dB above the minimum response threshold. Asterisks indicate statistically significant differences using an unpaired t test (p < 0.05). F, Mean ± SEM first spike latency as a function of BF for MGB and cortex and characteristic frequency for auditory nerve fiber recordings. Bins are 0.5 octaves wide beginning at the value indicated by the tick label. Norm., Normalized; Aud. N., auditory nerve.