Fig. 6. Both week-to-week fluctuation and trial-to-trial variation within the week is restricted to non-coding directions.
a TCA components of one imaging field (n = 166). We ordered components by the time to peak in their temporal factors. We ordered neurons in the neuron factors by their dominant components. Colormap maximum values are set to 2 for all the factors. b Left: two-dimensional neural manifold extracted from reconstructed (denoised) ΔF/F population activity (n = 166) across weeks using Isomap. Each dot represents instantaneous population activity in the test set. The color of the dot (same colormap as Fig. 4a) indicates the corresponding time in the trial. The black line is the fitted spline to the training set. Right: zoom-in view on the neural manifold. Instantaneous population activity corresponding to 28 s in the trial was highlighted with black shade. The Blue arrow denotes the direction perpendicular to the spline, and the red arrow denotes the direction parallel to the spline. c Histogram of the variance of population activity parallel or perpendicular to the spline for the imaging field shown in (a, b). d Median variance of population activity parallel to the spline plotted against median variance of population activity perpendicular to the spline for all the imaging fields. The variance of population activity parallel to the spline was significantly smaller than the variance perpendicular to the spline for most imaging fields (one-sided Wilcoxon signed-rank test, 350 timepoints, p-values for different imaging fields are 3.93 × 10−31 (n = 63), 2.61 × 10−55 (n = 84), 1.78 × 10−40 (n = 140), 2.61 × 10−58 (n = 150), 2.91 × 10−59 (n = 166), 7.37 × 10−57 (n = 185), 2.06 × 10−59 (n = 293), 3.03 × 10−31 (n = 353)), except for two imaging fields (p = 1.0 (gray, n = 49) and p = 0.997 (brown, n = 88)). The two outliers are from two imaging fields whose neural manifold didn’t have a clear ring shape (Supplementary Fig. 5a). e The same zoom-in view on the neural manifold as shown in (b) (right). Each triangle represents instantaneous population activity within a week. The color of the triangle denotes different weeks. Each cross represents the trial-averaged instantaneous population activity within a week. The color of the cross also denotes different weeks. f Left: histogram of the variance of trial-averaged population activity within a week parallel or perpendicular to the spline for the imaging field. Right: histogram of the variance of single-trial population activity within a week parallel or perpendicular to the spline for the imaging field. g Median variance of trial-averaged population activity or single-trial population within a week parallel to the spline plotted against median variance of population activity perpendicular to the spline for all the imaging fields. Y-axis is clipped at 9 for visualization. The variance of population activity parallel to the spline was significantly smaller than the variance perpendicular to the spline for both across weeks and within a week cases for most imaging fields (across weeks: one-sided Wilcoxon signed-rank test, 350 timepoints, p-values for different imaging fields are 1.45 × 10−27 (n = 63), 1.41 × 10−39 (n = 84), 1.55 × 10−33 (n = 140), 5.13 × 10−57 (n = 150), 8.50 × 10−58 (n = 166), 1.29 × 10−54 (n = 185), 1.26 × 10−57 (n = 293), 1.25 × 10−29 (n = 353), two outliers p = 1.0 (gray, n = 49), p = 0.99 (brown, n = 88); within a week: one-sided Wilcoxon signed-rank test, number of samples = 350 timepoints × number of weeks, p-values for different imaging fields are 7.36 × 10−97 (n = 63), 1.04 × 10−219 (n = 84), 1.53 × 10−177 (n = 140), 6.13 × 10−171 (n = 150), 6.23 × 10−273 (n = 166), 0.0 (n = 185), 0.0 (n = 293), 2.99 × 10−120 (n = 353), two outliers p = 1.0 (gray, n = 49), p = 1.0 (brown, n = 88)).