Fig. 8: Itgb1 cKO in MGs specifically interrupts the physical and functional interactions between AISa-MGs and PNs and affects visual discrimination behavior.

a Representative images of ITGB1 immunostaining of MGs in V1 of WT vs Itgb1 cKO mice. Scale bar, 2 μm. b ITGB1 expression on microglial processes of WT vs Itgb1 cKO mice (WT: 0.24 ± 0.02, n = 4 mice, vs Itgb1 cKO: 0.08 ± 0.00, n = 4 mice; two-sided Mann–Whitney test). c Representative confocal images showing physical interactions between MGs and AISs in WT vs Itgb1 cKO mice. Scale bar, 10 μm. d Percentages of MGs interacting with neuronal AISs (Itgb1 cKO: 6.61% ± 1.40%, n = 4 mice vs WT: 20.98% ± 1.24%, n = 4 mice; two-sided unpaired t-test). e Schematic of the experimental procedure. f Peak ΔF/F values (WT: 1.91 ± 0.05 vs Itgb1 cKO: 1.69 ± 0.04; n = 315 cells from 4 WT mice; n = 286 cells from 4 cKO mice; two-sided Mann–Whitney test). g Calcium transient frequency (WT: 4.02 ± 0.24 vs Itgb1 cKO: 3.06 ± 0.16; n = 315 cells from 4 WT mice; n = 286 cells from 4 cKO mice; two-sided Mann–Whitney test). h Samples of calcium transient traces of PNs in response to visual stimulation. i Example of the synchronicity and connectance of calcium responses among neurons within one neural ensemble. Lines represent connectance, and line colors represent synchronicity. Scale bar, 50 μm. j Synchronicity (left) (WT: 1.00 ± 0.06 vs Itgb1 cKO: 0.52 ± 0.04; n = 4 mice; two-sided unpaired t-test) and connectance (right) (WT: 1.00 ± 0.07 vs Itgb1 cKO: 0.39 ± 0.07; n = 4 mice; two-sided unpaired t-test) of calcium responses among neurons of neural ensembles. k Schematic of the experimental procedure. l Performance in the visual discrimination task during 5 days of training (n = 5 mice). m Representative examples showing licking behaviors of WT and Itgb1 cKO mice presented with Go and No-Go stimuli on day 5 of training. n Performance was significantly reduced by Itgb1 cKO in MGs (Performance: Itgb1 cKO: 51.43 ± 4.13 vs WT: 87.21 ± 2.93; two-sided unpaired t-test. Hit: Itgb1 cKO: 98.34 ± 0.21 vs WT: 99.46 ± 0.33; two-sided Mann–Whitney test. FA: Itgb1 cKO: 46.92 ± 4.30 vs WT: 12.25 ± 2.86; two-sided unpaired t-test. n = 5 mice). o Working model: The neuronal AIS and microglial process are physically bound together by the cell adhesion protein ITGB1. Visual stimulation (sensory input) in vivo induces transient depolarization selectively on the process of the AISa-MG interacting with the neuronal AIS through the acetylcholine (ACh)-muscarinic receptor (MR)-Na⁺ channel NALCN pathway. Transient depolarization on the AISa-MG process triggers K⁺ release through THIK-1 channels directly to the AIS and promotes AP firing of the small portion of associated PNs. This subsequently increases the coordinated activity of the entire neural ensemble, contributing to visual perceptual behaviors. Whiskers of box plots extend to the 2.5th and 97.5th percentiles of the data. Error bars indicate SEM.