Figure 1.

Labeling and imaging thalamocortical synapses on L4 or L5 barrel cortex neurons using array tomography and electron microscopy. (A1) Low power fluorescence photomicrograph of tdTomato-expressing TC axons and terminals in a fixed section of barrel cortex prepared from an 5–6 month old mouse in which AAV-tdTomato was stereotaxically injected in VPm 20–30 days earlier (inset left shows schematic of VPm injection). (A2) Low power fluorescence photomicrograph of GFP fluorescence in neurons in L4 barrel cortex in a fixed section from adult six3-CRE mouse in which AAV-FLEX-revGFP virus was injected into L4, 20-30 days earlier. (A3) Low power fluorescence photomicrograph of GFP fluorescence in L5 pyramidal neurons in fixed section from a 5–6 month old Thy1-YFP_h mouse. (B) Schematic of LR white embedding and ultrathin serial sectioning procedure. (C) Schematic of immunostaining and light imaging of serial sections. (D1) Schematic of light and electron microscopic imaging on the same sections to assess accuracy of synapse detection and annotation with array tomography (performed on VPm-L4 only). (D2) Reconstructed L5 pyramidal neuron and annotated TC synapses from large-scale array tomography experiment (VPm-L5 only).