<i>In vivo</i> drug application in immature cortex.

<p>(A) Upper left: Two-photon image of Venus positive cells immediately after drug application in a P0 VGAT-Venus mouse. Making a hole at 1–2 mm away from the observed area has no effect on the morphology of the cells within imaging area. Scale bar = 50 µm. Lower left: Two-photon image of sulforhodamine 101 (SR101) showing that the drug does not reach the imaging area immediately after injection. Upper right: Schematic drawing of the drug injection procedure; making a hole and injecting the drug conjugated with SR101. The drug diffuses into the imaging area after 30–60 minutes of injection. Lower right: Two-photon image of Venus-positive cells and SR101 showing that the pipette solution spread around the cells without injuring them. Scale bar = 50 µm (B) Cell displacement during 1 hour of migration for neurons in VGAT-Venus without drug application (VGAT), after injection of ACSF (+ ACSF) and after injection of SR95531 (+SR95531). The selective GABA_AR antagonist (SR95531, 1 mM, 1 µl) reduced the migration rate significantly (*p<0.05) whereas ACSF (1 µl) had no effect. (C) DMSO (1 µl) had no effect on cell displacement. Chelating intracellular Ca²⁺ by BAPTA-AM (2 mM, 1 µl) conjugated with DMSO almost completely inhibited the migration (**p<0.01) and blockade of NKCC by bumetanide (1 mM, 1 µl) significantly reduced the migration rate (*p<0.05). VGAT-Venus; n = 5 animals, ACSF; n = 5 animals, DMSO; n = 4 animals, SR95531; n = 5 animals, bumetanide; n = 4 animals, BAPTA-AM; n = 4 animals. All animals were used at P0–P3, except the bumetanide group which were used at P1–P3. Each column in B and C indicates mean ± SEM.