Fig. 6: Interaction structure is distinct for the feedforward- and feedback-dominated periods.

a The dimensions found by fitting CCA shortly after stimulus onset (80 ms after stimulus onset) do not generalize well to later epochs in the evoked period, and worse still during the spontaneous period. Gray lines correspond to each of the 5 recording sessions. We report the normalized correlation, defined as the total correlation captured at the test epoch by the dimensions fit to some other epoch over the total correlation captured by the dimensions fit the test epoch (both computed in a cross-validated manner; see Methods). b Dimensions identified late in the evoked period (1180 ms after stimulus onset) do not generalize well to early evoked epochs and to epochs in the spontaneous period, but generalize well to mid-evoked activity. Same conventions as in a. c Dimensions identified during the spontaneous period do not generalize well to the evoked period. Same conventions as in a. d Assessing changes in interaction structure across the entire trial. The trial was divided into 100 ms segments, and CCA was applied separately to the activity in each time window. The top two canonical pairs associated with each window were then used to capture inter-areal correlations in the other time windows (see Methods). Each row corresponds to the time during the trial during which the canonical dimensions were identified. Each column corresponds to the time during the trial where the population correlation is assessed. Each entry shows the average across all recording sessions. Straight arrow highlights the comparison of the interaction structure within the evoked period. Curved arrow highlights the comparison of the interactions structure between the spontaneous and the evoked periods. Dashed white boxes indicate epochs reproduced in f. e Comparing identified dimensions across epochs for the awake V1–V4 recordings. The trial was divided into 100 ms segments, and CCA was applied separately to the activity in each time window. The top canonical pair associated with each window was then used to capture inter-areal correlations in the other time windows (see Methods). Arrow highlights the comparison of the interaction structure within the evoked period. Same conventions as in d. f Detailed view of the V1–V2 generalization performance for the comparable epochs between the V1-V2 and V1-V4 recordings. Epochs are indicated by the dashed white boxes in d.