Figure 2.

Intracortical input linearly amplifies frequency-tuned thalamocortical input. (a) Average tone-evoked excitatory currents in an example cell at different frequencies without (black) and with (blue) LED illumination. The envelope curve outlines the frequency tuning of peak amplitude. Scale: 0.05 nA, 200 ms. (b) Left, peak amplitude of thalamic input versus total excitation evoked by the same tone stimulus. Linear fitting: r = 0.91, slope = 0.32, P < 1e-8, one-tail. Inset, the two envelope curves from a (normalized and superimposed). Right, onset latencies of thalamocortical (blue) and total (red) excitatory responses at different frequencies. (c, d) Another example cell. Scale: 0.035 nA, 200 ms. Linear fitting: r = 0.77, slope = 0.76, P = 3.4e-6, one-tail. (e) Total frequency range of thalamic input versus total excitation (2.74 ± 0.61 vs. 2.79 ± 0.61 octave, P = 0.38, Wilcoxon signed-rank test). Each data point represents one cell. (f) BW50% of thalamic input versus total excitation (1.79 ± 0.61 vs. 1.84 ± 0.57, P = 0.49, paired t-test). (g) Average peak amplitude of thalamic input versus total excitation (0.03 ± 0.03 vs. 0.07 ± 0.05 nA, P = 1.9e-4, paired t-test). (h) Response duration of thalamic input (measured at 10% of the maximal amplitude of BF-tone responses) versus total excitation (51.17 ± 22.06 vs. 92.99 ± 44.8 ms, P = 3.66e-4, Wilcoxon signed-rank test). Inset, average response traces without (black) and with (blue) LED illumination of an example cell. Scale: 0.04 nA, 50 ms.