Tuning curves were derived by measuring mean response amplitudes over 10 ms periods, centered between 23 and 30 ms following the stimulus onset at a recording depth within the Layer 4 (see methods). The mean amplitude of MUA, CSD and LFP signals indicated change in the level of local neuronal firing, the magnitude of current sinks due to excitatory synaptic currents and the magnitude of LFP negativity caused by current sinks relative to the baseline levels, respectively. The period was chosen to be the time during both LFP and CSD signals were negatively deflected along with simultaneous increase in MUA. Figure 3A and B show the normalized tuning curves for LFP, CSD and MUA signals in the two example cases shown in Fig. 2A and B, respectively. The three types of tuning curve generally peak at the same tone frequencies. The same trend was observed across all recording sites (Fig. 3C). BF estimates were not significantly different between the 3 signals (Friedman's non-parametric repeated measures ANOVA, χγ2 (2, n=130) = 0.92, p = 0.2, Fig. S1). The tuning bandwidths of
