Visualizing Somatosensory Cortex Projections

EGFP-Cre (Addgene) was cloned into the pAAV-MCS vector (Stratagene). The resultant recombinant viral vector was packaged in the capsid of serotype 8, and high-titer virus (approximately 10¹³ genome copy (gc)/ml) was produced by Harvard Gene Therapy Initiative (HGTI). To visualize the projections from the somatosensory cortex, 1–2 μl of rAAV-EGFP-Cre (1.6 × 10¹³ gc/ml) was injected into anesthetized Ai14 mice at corresponding stereotaxic coordinates using a glass micropipette attached to a Picospritzer (Parker Hannifin). The virus was administered slowly by a number of low pressure air puffs to minimize tissue damage (10 psi, 10–20 ms duration, 2 Hz and 10 min/μl). Mice were then recovered and housed individually until they were utilized for further analysis.