Fig. 4: Auditory input does not influence dendritic integration, nor somatic output, in layer 5 pyramidal neurons.

Two-photon Ca²⁺ imaging in the dendrites of L5 pyramidal neurons. a Example field of view. Imaging depth, 40 μm below pia. Scale bar, 10 μm. b Ca²⁺ transients from a tuft dendrite shown in (a) during tactile stimulus alone (black) and paired with auditory stimulus (AudTac, red). c The amplitude of Ca²⁺ transients in L5 tuft dendrites during tactile stimulus alone (black; n = 112 dendrites, 4 mice; 27 trials_av) and paired with auditory stimulus (red; n = 106 dendrites, 4 mice; 24 trials_av; p = 0.794; p_shuffled = 0.960; Mann–Whitney test). d Imaging depth, 300 μm below pia. e Same as (b) for L5 apical dendrites. f Same as (c) for L5 apical dendrites (n = 44 dendrites, 4 mice; 26 trials_av; p = 0.755; p_shuffled = 0.931; Mann–Whitney test). g Amplitude of all Ca²⁺ transients in L5 apical (L5A; n = 43/32), L5 tuft (L5T; n = 100/109) and L2/3 tuft (L2/3 T; n = 143/130) dendrites during AudTac stimulus (red) and auditory stimulus (blue) normalized to the response to tactile stimulus. One-way ANOVA Friedman test, p < 0.0001, p = 0.0005. h Same as (g) for probability of evoked Ca²⁺ transients. One-way ANOVA Friedman test, p < 0.0001, p < 0.0001. i Schematic of experimental paradigm. Patch-clamp recordings were performed from L5 pyramidal neurons in forepaw S1 from naive mice in the awake state. Inset, example voltage response to injected 50 pA steps of current. Scale, 20 mV, 400 ms. j (Top) Overlay of individual trials, (middle) average subthreshold voltage, and (bottom) raster of action potentials from a typical neuron in response to tactile stimulus (black), paired auditory and tactile stimulus (red) and auditory stimulus (blue). Colored trace, single example trace. k Evoked action potentials in response to tactile (black), paired auditory and tactile (red), auditory (blue) and baseline (gray) (n = 16 neurons, 5 mice; 17 trials_av) One-way ANOVA Friedman test. Error bars represent S.E.M. *p < 0.05.