First, a Teal insert was generated by PCR amplification of Teal (Allele Biotech, San Diego, CA, USA) with added 5′ NheI and 3′ EcoRI restriction sites and subcloned into the pLL3.7syn lentiviral expression plasmid. Next, Gephyrin with 5′ BsrGI and 3′ MfeI restriction sites was generated by PCR amplification from a GFP-Gephyin expression plasmid ( Fuhrmann et al., 2002) and subcloned into the Teal expression plasmid using the BsrGI and EcoRI sites to generate a Teal-Gephryin fusion protein. Finally, Teal-Gephyrin with 5′ BsiWI and 3′ NheI restriction sites was

PCR amplified from this plasmid and subcloned into the Cre-dependent eYFP expression plasmid described above, replacing eYFP in the dio expression cassette. All animal work was approved by the Massachusetts Institute of Technology Committee on Animal Care; it conforms to the National Institutes of Health 17-AAG guidelines for the use and care of vertebrate animals. L2/3 cortical pyramidal neurons were labeled by in utero electroporation

on E16 timed pregnant FG-4592 cost C57BL/6J mice (Charles River, Wilmington, MA, USA) as previously described (Tabata and Nakajima, 2001). pFUdioeYFPW, pFUdioTealGephyrinW, pFUCreW plasmids were dissolved in 10 mM Tris ± HCl (pH 8.0) at a 10:5:1 molar ratio for a final concentration of 1 μg/μl along with 0.1% of Fast Green (Sigma-Aldrich, St. Louis, MO, USA). The solution, containing 1-2 μl of plasmid, was delivered into the lateral ventricle with a 32 gauge Hamilton syringe (Hamilton Company, Reno, NV, USA). Five pulses of 35–40 V (duration 50 ms, frequency 1 Hz) were delivered, targeting the visual cortex, using 5 mm diameter tweezer-type platinum electrodes connected to a square wave electroporator (Harvard Apparatus, Holliston, MA, USA). Mice born after in utero electroporation were bilaterally implanted with cranial windows at postnatal days Mephenoxalone 42–57 as previously described (Lee et al., 2008). Sulfamethoxazole (1 mg/ml) and trimethoprim (0.2 mg/ml) were chronically administered in the drinking water through the final imaging session to maintain optical clarity of implanted windows. For functional identification of monocular and binocular visual cortex,

optical imaging of intrinsic signal and data analysis were performed as described previously (Kalatsky and Stryker, 2003). Mice were anesthetized and maintained on 0.5%–0.8% isofluorane supplemented by chloroprothixene (10 mg/kg, i.m.) and placed in a stereotaxic frame. Heart rate was continuously monitored. For visual stimuli, a horizontal bar (5° in height and 73° in width) drifting up with a period of 12 s was presented for 60 cycles on a high refresh rate monitor positioned 25 cm in front of the animal. Optical images of visual cortex were acquired continuously under 610 nm illumination with an intrinsic imaging system (LongDaq Imager 3001/C; Optical Imaging Inc., New York, NY, USA) and a 2.5×/0.075 NA (Zeiss, Jena, Germany) objective.