Glass pipette and nanoject system

All viruses used to locally infect V1 were adeno-associated viruses (AAV). For optogenetic experiments we infected V1 of ~1 month old mice expressing Cre recombinase directed by the parvalbumin promoter (B6;129P2-Pvalb^tm1(cre)Arbr/J – Jackson laboratory, ME, US) or wild-type littermates with AAV5-EF1α-DIO-hChR2(H134R)-eYFP (UNC viral core – generated by Dr. Karl Deisseroth’s laboratory). Using a glass pipette and nanoject system (Drummond scientific, Broomall, PA, US) we delivered 81 nl of virus at each of 3 cortical depths: 600 μm, 450 μm and 300 μm below surface. At each depth 6 injections of 13.5 nl were delivered, each separated by 15 secs, and 5 mins was allowed between re-positioning for depth. For local GRIN1 knockdown, ~1 month old mice GRIN^fl/fl mutant mice (B6.129S4-Grin1^tm2Stl/J – Jackson laboratory) were infected locally in V1 with either AAV8-hSyn-GFP-Cre (knockdown, UNC viral core) or AAV8-hSyn-GFP (control, UNC viral core – generated by Dr Bryan Roth’s laboratory). Again, injections were made at multiple depths. In this case 10 injections of 13.5 nl were made for a total of 135 nl at 4 cortical depths: 600 μm, 450 μm, 300 μm and 150 μm below surface. As before, each injection was separated by 15 secs, and 5 mins was allowed between re-positioning for depth. Mice were allowed 4 weeks recovery for virus expression to peak before experiments were initiated.