Young adult (postnatal day 42–98) male C57BL/6J (Jackson Labs) mice were anaesthetized using isoflurane (2.5% for induction and 1.5% during surgery). A circular craniotomy (diameter of 3 mm) above medial crus I (2 mm left and 1 mm posterior to the midline junction of the interparietal and occipital bones). Viral suspension (200 nl) was injected in two locations near the centre point at a depth of 300–400 μm. Constructs injected included: AAV2/1-CAG-FLEx-jGCaMP8 constructs (pGP-AAV-CAG-FLEx-jGCaMP8f-WPRE, Addgene plasmid #162382; pGP-AAV-CAG-FLEx-jGCaMP8m-WPRE, Addgene plasmid #162381; pGP-AAV-CAG-FLEx-jGCaMP8s-WPRE, Addgene plasmid #162380; pGP-AAV-CAG-FLEx-jGCaMP7f-WPRE, Addgene plasmid #104496; and pGP-AAV-CAG-FLEx-jGCaMP6f-WPRE, Addgene plasmid #100835; all viruses were diluted to 4 × 1012 GC per millilitre titre).
Purkinje cell-specific expression was induced by co-injection of virus expressing Cre under control of a promoter fragment from the Purkinje cell protein 2 (Pcp2; also known as L7) gene (AAV2/1-sL7-Cre, 5.3 × 1010 GC per millilitre titre)68 (link). A 3-mm diameter circular coverslip glued to a donut-shaped 3.5-mm diameter coverslip (no. 1 thickness, Warner Instruments) was cemented to the craniotomy using dental cement (C&B Metabond, Parkell). A custom titanium head post was cemented to the skull.
Purkinje cell-specific expression was induced by co-injection of virus expressing Cre under control of a promoter fragment from the Purkinje cell protein 2 (Pcp2; also known as L7) gene (AAV2/1-sL7-Cre, 5.3 × 1010 GC per millilitre titre)68 (link). A 3-mm diameter circular coverslip glued to a donut-shaped 3.5-mm diameter coverslip (no. 1 thickness, Warner Instruments) was cemented to the craniotomy using dental cement (C&B Metabond, Parkell). A custom titanium head post was cemented to the skull.