The organization and development of cortical interneuron presynaptic circuits are area specific

A versatile viral toolkit for functional discovery in the nervous system

“…In conjunction with the hDlx enhancer, we observed that the vast majority of cells expressing the viral reporter were SOM+ ( Figures 3 D and S3 B; SOM+: 83.17% ± 5.95%; other GABAergic, with parvalbumin [PV]: 8.97% ± 2.67%; vasoactive intestinal peptide [VIP]: 5.5% ± 1.22; N = 3). VTKS5-Rabies-Helper (Cre-ON; Flp-OFF) was injected in Lhx6-iCre::Sst-FlpO, which led to a strong transgene expression de-targeted from SOM interneurons ( Pouchelon et al., 2021 ) ( Figure 3 E; SOM-: 97.42% ± 0.19%, N = 3). VTKD6-APEX2-V5 (Cre-OFF; Flp-ON) was injected into the hippocampus ( Figure 3 F, S1 , S3 A, and S3B) of ACTB-FlpE::SST-Cre animals.…”

“…The rabies helper transgenes required for monosynaptic retrograde labeling include the coding sequence of a reporter, the cellular receptor for subgroup A avian leukosis viruses (TVA), and rabies glycoprotein, amounting to a 3 kb construct. These transgenes were integrated into VTKS5 and injected into the somatosensory cortex of Lhx6-iCre::SSTFlpO mice ( Pouchelon et al., 2021 ). Following injection of rabies viruses, we observed monosynaptic retrograde labeling from the AAV-targeted cells in the expected thalamic nucleus ( Figure 4 E).…”

“…VTKS/D constructs containing the promoter and inducible sites were synthesized (see Table S2 ) and cloned using ApaI/AscI into a backbone containing ITRs, WPRE and bGHp polyA (from Addgene #52473, a generous gift from Ian Wickersham) ( Kohara et al., 2014 ). For VTKS1-hChR2-tBFP, we cloned the hChR2 coding sequence from the Addgene plasmid #26976 (a generous gift from Karl Deisseroth) and tBFP from the Addgene plasmid #80086 (a generous gift from Connie Cepko); for VTKS2-hM3Dq-P2A-tBFP, we amplified the hM3Dq-P2A coding sequence from Addgene plasmid #83897 ( Chen et al., 2020 ) and tBFP from the Addgene plasmid #80086; for VTKS3-TeTLc-P2A-mCherry, the coding sequence of TeTLc-P2A-mCherry was a generous gift from Rosa Cossart; for VTKD4-V5-APEX2-NES and VTKD6-V5-APEX2-NES, we amplified the V5-APEX2-NES coding sequence from the plasmid Addgene #72480 (a generous gift from Alice Ting); for VTKS5-N2cG-P2A-eGFP-P2A-TVA, we amplified the eGFP-P2A-TVA coding sequence from Addgene plasmid #52473 (a generous gift from Tom Jessell) and we cloned N2cG from pAM-CAGGS-FLEX-H2B-GFP-P2A-N2c(G ) ( Pouchelon et al., 2021 ).…”

Improvement of sensory deficits in Fragile X mice by increasing cortical interneuron activity after the critical period

“…1F ). Somatostatin-expressing INs (SST-INs) and PV-INs both arise from a common precursor in the MGE (Marques-Smith et al, 2016; Pouchelon et al, 2021; Tuncdemir et al, 2016). Therefore, we also imaged the activity of SST-INs in vivo at P15 in Sst - FlpO +/− mice injected with AAV8-Ef1a-fDIO-GCaMP6s ( Fig.1SA,B ).…”

“…We next investigated whether early GABAergic interneuron activity during the first neonatal week contributes to the previously described early signs of cortical circuit dysfunction (e.g., excess synchrony in neonatal mice) (La Fata et al, 2014). Cortical PV-INs do not express PVALB before P10 (Butt et al, 2008; de Lecea et al, 1995; Pouchelon et al, 2021), but their precursors from the MGE can be identified through their expression of the transcription factor Nkx2.1 . We used in vivo calcium imaging to record from MGE-INs at P6 in Nkx2.1-Cre mice injected with AAV1-CAG- Flex-GCaMP6s into S1 at P1 ( Fig.…”