Journal: bioRxiv

Article Title: Mechanistic basis of dynamic and heterogeneous divisive normalization in visual cortex

doi: 10.1101/2025.08.19.671076

Figure Lengend Snippet: Experimental setup and basic description of normalization in mouse V1. (A) : Example imaging field of view in superficial mouse V1, with average GCAMP fluorescence in white and tdTomato expression in magenta. Colocalization of white and magenta indicates PV interneurons expressing GCaMP. (B): Example visual stimuli: large static sine-wave gratings at 50% contrast and the corresponding 100% contrast plaid resultant from summing two orthogonal gratings. (C): Example orientation tuning curves and responses to plaids at the preferred orientation for two recorded neurons, one with a positive normalization index (NI) corresponding to cross-orientation suppression, and one with a negative NI corresponding to facilitation. (D): Distribution of normalization indices (NI) for PV (N=78) and putative excitatory (N=1,325) cells pooled across mice, computed from the inferred spiking activity across the whole stimulus presentation. The median values for PV and E NI distributions, 0.23 and 0.31 respectively (indicated by dashed vertical lines), are not significantly different ( p = 0.222, Wilcoxon rank-sum test).

Article Snippet: At each injection site we lowered a glass-tipped syringe controlled by a microsyringe pump into the brain and injected 200nL of AAV9 synapsin-promoted GCaMP virus (pAAV.Syn.GCaMP6f.WPRE.SV40, Addgene product #100837 for GCaMP6f mice, pGP-AAV-syn-jGCaMP8s-WPRE, Addgene product #162374 for GCaMP8s mice) at two depths, roughly 250 and 500 microns below pia.

Techniques: Imaging, Fluorescence, Expressing, Activity Assay