Fig. 1: Tonal receptive fields obtained from in vivo current-clamp whole-cell recordings to pure tones.

a A representative example with a high normalized-driven ratio of 0.57. This example had a characteristic frequency of ~17 kHz and a bandwidth30 of ~1 octave within a TRF region (the shaded area). Horizontal scale: 1 s; vertical scale: 30 mV. The inset on the right shows an enlarged view of one representative trace obtained from a tone among a set of 360 combinations. Scale bar, 0.1 s. b A representative example with a low normalized-driven ratio of 0.02. The neuron had a characteristic frequency of ~17 kHz and a bandwidth30 of ~1.7 octaves within a TRF region. Spikes have been truncated to illustrate relatively small subthreshold membrane potential responses well. Horizontal scale: 1 s; vertical scale: 10 mV. The inset on the right shows an enlarged view of one representative trace obtained from a tone among a set of 360 combinations. Scale bar, 0.1 s. c Histogram of resting membrane potentials (n = 66 neurons from 41 mice). d Histogram of normalized-driven ratios (n = 66). e Relationship between normalized-driven ratios and resting membrane potentials. f Histograms of the bandwidth30s of PSPs (normalized-driven ratio < 0.3, n = 35, dark gray; normalized-driven ratio ≥0.3, n = 31, light gray). g Histogram of the bandwidth30s of spikes (n = 31/66 with normalized-driven ratio ≥0.3). h Relationship between the bandwidth30s of PSPs and the bandwidth30s of spikes (n = 31/66 with normalized-driven ratio ≥ 0.3). The two groups were statistically significantly different (two-tailed paired Student’s t-test; p = 10⁻⁶). On the right, the box plot indicates ratios of the spike bandwidth30 to the PSP bandwidth30. The lower and upper hinges are at the 25th and 75th percentiles. The median by the middle line between hinges was 0.89. Asterisks indicate outliers. The minimum value is marked by the lower whisker.