Mice were allowed to recover for 2–4 weeks to allow for viral expression before electrophysiology and imaging were performed. See Supplemental Experimental Procedures for details. Standard artificial cerebrospinal fluid (ACSF) consisted of NaCl (125 mM), NaHCO3 (25 mM), KCl (2.5 mM), NaH2PO4 (1.25 mM), 3-MA molecular weight MgCl2 (1 mM), CaCl2 (2 mM), glucose (22.5 mM), Na-pyruvate (3 mM), ascorbate (1 mM). Sucrose-enriched modified dissection

ACSF contained NaCl (10 mM), NaH2PO4 (1.2 mM), KCl (2.5 mM), NaHCO3 (25 mM), glucose (25 mM), CaCl2 (0.5 mM), MgCl2 (7 mM), sucrose (190 mM), pyruvate (2 mM). The ACSF had a pH of 7.3, osmolarity of 305–320 mOsm, and was saturated with 95% O2 and 5% CO2. The intracellular solution contained KMeSO4 (135 mM) (for current-clamp recordings) or CsMeSO4 (135 mM) (for voltage-clamp recordings), KCl (5 mM), NaCl (2 mM), EGTA (0.2 mM), HEPES (10 mM), phosphocreatineNa2 (10 mM), MgATP (5 mM), Na2GTP (0.4 mM), Alexa Fluor 594 (0.1 mM), and Biocytin (0.2%). In a subset of experiments, the following drugs (Tocris) were used at the following concentrations via bath application (unless otherwise noted): SR95531 (2 μM), CGP55845 (1 μM), AM251 (2 μM), NBQX (10 μM), D-APV (100 μM), and LY 367385 (100 μM). RuBiGABA was obtained from Tocris

or Ascent and PSEM308 was a generous gift from Scott Sternson and used at a concentration of 5 μM and 3 μM, respectively. A vibrating microtome (Vibratome 1000 or Leica CP-690550 solubility dmso VT1200S) was used to obtain 400-μm-thick horizontal or transverse sections of brains from mice that were transcardially perfused with ice-cold dissection ACSF. Slices were allowed to recover for at least 30 min at 34°C and then Thalidomide stored at room temperature in a 50% dissection:

50% standard ACSF solution. Infrared- or fluorescence-guided whole-cell patch-clamp recordings were performed at 34°C in standard ACSF. Fire-polished borosilicate glass pipettes (Sutter) were used with tip resistances of 3.5–4.5 MΩ for somatic and 8–10 MΩ for dendritic recordings. A Multiclamp 700B Amplifier and pClamp 9 software (Axon Instruments) were used for data acquisition. The average series resistance for whole-cell voltage-clamp recordings was kept between 9–15 MΩ; 75%–80% of the resistance was compensated. Current-clamp recordings were obtained with access resistances of 10–20 MΩ for the soma and 10–40 MΩ for the dendrites, compensated in bridge mode. ITDP was induced by paired PP and SC electrical stimulation at a −20 ms interval (PP before SC) at 1 Hz for 90 s using focal glass pipette-stimulating electrodes coupled to constant current stimulators (WPI). Stimulus strengths were adjusted so that PP and SC PSPs were less than 50% of their maximal amplitude (typically <0.5 mV for PP and <5 mV for SC).