Figure 2. High correlation of calcium transients between neuronal compartments (soma, trunk, apical tuft) of individual layer 5 neurons.

(A) Anatomical reconstruction of an individual GCaMP6s-labeled layer 5 pyramidal neuron imaged at two focal planes semi-simultaneously (red dotted lines, proximal; blue, distal). Left panel, coronal and horizontal views of the same imaged neuron. Right panel, two-photon image of dendritic branches highlighted in red and blue in the horizontal view of the anatomical reconstruction. Example ΔF/F0 traces of highly correlated calcium transients from dendritic branches indicated in red and blue. (B) Schemata of the compartments imaged semi-simultaneously, (i) proximal tuft-distal tuft, (ii) trunk-tuft, (iii), trunk-trunk, (iv) soma-trunk. pTrunk, dTrunk and pTuft, dTuft indicate proximal and distal portions of the trunk and the apical tuft, respectively. (C) Left panel, representative GCaMP6s transients imaged in two neuronal compartments semi-simultaneously as shown in B. Right panel, scatter plot of peak amplitudes of individual calcium transients in proximal and distal compartments imaged semi-simultaneously, in one example individual neuron. Each dot represents a calcium transient. Peak amplitudes were normalized to the maximum amplitude in each compartment. Filled dots correspond to the transients indicated by numbers in the left panel. Red dotted line indicates the best fit (least square). Pearson’s correlation values (r) are indicated for each example pair of neuronal compartments. Scale bars 0.3 ΔF/F0 (normalised to max), 10 s. (D) Pearson’s correlation values for each pair of compartments imaged semi-simultaneously and corresponding shuffled data (Paired t-test, (i)pTuft-dTuft, p=1.6e⁻⁶, mean = 0.88; −0.01, sem = 0.02; 0.02, n = 6 pairs; (ii)Trunk-Tuft, p=8e⁻⁷, mean = 0.92; 0.04, sem = 0.02; 0.07, n = 9; (iii) pTrunk-dTrunk, p=4.4e⁻⁴, mean = 0.85; −0.05, sem = 0.05; 0.07, n = 5; (iv) Soma-Trunk, p=4.4e⁻⁶, mean = 0.74; 0.05, sem = 0.04; 0.06, n = 11).

Figure 2—figure supplement 1. Scatter plots of peak amplitudes of individual calcium transients in all proximal and distal compartments imaged semi-simultaneously.

Each dot represents a calcium transient. Peak amplitudes were normalized to the maximum amplitude in each compartment. x-axis: proximal compartment; y-axis: distal compartment. Black line indicates the identity line. The mean Pearson’s correlation values (r) calculated per neuron, as reported in Figure 2D (i–iv), are indicated for each pair of compartment. Soma-Trunk, n = 858 transients from 11 neurons; pTrunk-dTrunk, n = 360 transients from 5 neurons; Trunk-Tuft, n = 479 transients from 9 neurons; pTuft-dTuft, n = 447 transients from 6 neurons; For visualization purpose, for Trunk-Tuft and pTuft-dTuft, only transients from one pair of imaged compartments per neuron are shown.

Figure 2—figure supplement 2. Most dendritic events detected as branch-specific were also detected in the trunk.

(A) Example ΔF/F0 traces of GCaMP6s calcium transients imaged semi-simultaneously in the trunk (red) and in two sibling apical tuft branches (black) of an individual layer 5 neuron. The asterisks indicate a calcium transient that was only detected in one of the two apical tuft branches (tuft 2) and thus classified as a branch-specific event. This transient was also detected in the trunk of the same neuron. Scale bars 0.25 ΔF/F0 (normalised to max), 20 s. (B) Proportion of apical tuft dendritic branch-specific events, as a function of GCaMP6s calcium transient amplitude. Black, all apical tuft dendrites events detected as branch-specific. Red, proportion of branch-specific events which were also simultaneously detected in the corresponding trunk. On average, 60% of branch-specific events were also found in the trunk.