Salts for all buffers

Salts for all buffers, as well as DA and DOPAC were purchased from Sigma Aldrich (St. Louis, MO, USA). The source of PTX was either Sigma Aldrich or Hello Bio Inc. (Princeton, NJ, USA), muscimol was from Tocris Bioscience (R&D Systems Inc., Minneapolis, MN, USA) or Hello Bio, D-AP5, DNQX and gabazine (SR 95531) were from Hello Bio, JNJ-16259685 and Dihydro-β-erythroidine hydrobromide (DHβE) were from Tocris Bioscience, and 3-mercaptopropionic acid (3-MPA), (+)bicuculline, strychnine hydrochloride were from Sigma Aldrich. Experimental solutions of PTX were prepared by vigorous stirring in aCSF for ~10 min immediately before use. 3-MPA was added to the recovery HEPES buffer for preincubation of slices and to aCSF during slice recordings. DNQX, JNJ-16259685 and (+)bicuculline were dissolved in dimethyl sulfoxide (DMSO, Sigma Aldrich) as stock solutions. Working solutions with the final experimental concentrations were prepared in aCSF immediately before use, with a maximal final DMSO concentration of <0.1%. All other drugs were prepared and stored as aqueous stocks in deionized water before dilution in aCSF.