Figure 6.

Imaging of ΔL-labeled neurons’ visual response properties over 16 weeks

(A) Experimental design for longitudinal functional two-photon imaging in vivo. ΔL virus expressing Cre was injected in the primary visual cortex of reporter mice expressing GCaMP6s³⁶ after Cre recombination, and then the injection sites were imaged while the awake mice were presented with drifting grating stimuli of different orientations and temporal frequencies repeatedly for 16 weeks following virus injection.

(B) Example FOV from a GCaMP6s imaging session 16 weeks after RV injection. Individual analyzed cells are randomly pseudocolored. Scale bar: 50 μm.

(C and D) Long-term stability of orientation and temporal frequency tuning in RVΔL-Cre-labeled neurons. The top rows show maximum intensity projections of the imaged GCaMP6s signal in two different FOVs at three different time points for each FOV. Scale bars: 20 μm, apply to all images. Visual response tuning curves of the two circled cells in each FOV at the corresponding time point, obtained with drifting gratings presented at 12 directions of motion and 5 temporal frequencies (TFs) (mean ΔF/F ± SEM, averaged over 10 repeats), are shown under each image.

(E) Percentages of labeled cells that were visually tuned (see STAR Methods) from 6 different FOVs in 3 mice imaged over 14 weeks. Connected sets of dots in a given color indicate data from a single mouse (data from 2 FOVs are shown per mouse).

(F) Comparison of the percentages of labeled cells that were visually tuned at 2 and 14 weeks. The percentages increased moderately but significantly between the two time points from 60% to 68% (paired two-sample t test, p = 0.0178, n = 6 FOVs across 3 mice).

(G) Although in general we were not able to track individual neurons over multiple imaging sessions due to limitations of our imaging capabilities, in some cases, we were able to do so. This graph shows the numbers of cells that were tuned at 4 weeks that were identifiable at 14 weeks and that were still tuned at that later time point: 94% of these neurons were still tuned at 14 weeks. Each dot represents the number of such cells within each FOV (n = 6 FOVs across 3 mice).