Bicuculline bic

Chemical LTP was induced in culture using 30 μM bicuculline (Bic, #0130, Tocris Bioscience, Bristol, UK) and 100 μM 4-Aminopyridine (4-AP, #275875, Sigma Aldrich). GluR inhibition was performed using 40 μM d(–)-2-amino-5-phosphonopentanoic acid (APV, #A8054, Sigma Aldrich) and 2 μM 6,7-dinitroquinoxaline-2,3-dione (DNQX, #D0540, Sigma Aldrich).

Whole-cell voltage-clamp and current-clamp recordings were collected, in an unblinded fashion, from pyramidal neurons, morphologically confirmed visually and with a cell capacitance criterion of >80 pF, and analyzed as previously described [40 (link), 41 (link)]. A K-gluconate internal solution was used to record spontaneous excitatory postsynaptic currents (sEPSCs) in artificial cerebrospinal fluid (ACSF), miniature excitatory postsynaptic currents (mEPSCs) in the presence of 30 µM bicuculline (BIC; Tocris) and 0.5 µM tetrodotoxin (TTX; Sigma Aldrich), and excitability in ACSF.
For optogenetic experiments, channelrhodopsin-2 (ChR2)-photocurrents were measured using wide-field illumination. Mono-synaptic connectivity was measured in ACSF containing 30 µM BIC, 0.5 µM TTX, and 100 µM 4-aminopyridine (4-AP). AMPA and NMDA currents were recorded from a holding potential of −80 mV and +40 mV, respectively, using an Cs-methanesulfonate internal solution. Data analysis was conducted in a blind fashion until the final step of grouping cells and statistics.