Acquisition boards

Membrane currents and potentials were amplified and low-pass filtered at 3 kHz using a Multiclamp 700B amplifier (Molecular Devices), digitized at 10 kHz and acquired using National Instruments acquisition boards and a custom version of ScanImage written in MATLAB (Mathworks). Electrophysiology data was analyzed offline using Igor Pro (Wavemetrics) and imaging data was analyzed using ImageJ (National Institutes of Health). Averaged waveforms of 3–5 consecutive sweeps were used to obtain current onset and peak current amplitude. Detection threshold for IPSCs and EPSCs was set at 10 pA. Current onset was measured using a threshold set at three standard deviations of baseline noise. Peak amplitudes were calculated by averaging over a 2 ms window around the peak. For experiments using drug perfusions, peak amplitudes of three consecutive light-evoked responses 3–4 min after drug perfusion onset were averaged, normalized to baseline averages and compared statistically with values obtained at corresponding times in control preparations bathed in ACSF. Data (reported in text and figures as mean ± s.e.m.) were compared statistically using a Mann-Whitney U test. P values less than 0.05 were considered statistically significant.

Membrane currents and potentials were recorded using an Axoclamp 700B amplifier (Molecular Devices, Sunnyvale, CA) filtered at 3 kHz and digitized at 10 kHz using National Instruments acquisition boards and ScanImage (available at: scanimage.org) written in MATLAB (Mathworks, Natick, MA). Electrophysiology and imaging data were analyzed offline using Igor Pro (Wavemetrics, Lake Oswego, OR), ImageJ (NIH, Bethesda, MD) and GraphPad Prism (GraphPad Software, La Jolla, CA). In figures, voltage-clamp traces represent the average waveform of 3–6 acquisitions. Peak current amplitudes were calculated by averaging over a 1 ms window around the peak. For pharmacological analyses, 3–7 consecutive acquisitions (20 s inter-stimulus interval) were averaged following a 3-min wash-in period for NBQX and CPP or a 4-min wash-in period for MEC, MLA, and DHβE. For TTX and 4AP conditions, current averages were composed of the acquisitions following full block or first-recovery of ChR2 evoked currents, respectively. Data (reported in text and figures as mean ± sem) were compared statistically using the Mann–Whitney test. p values smaller than 0.05 were considered statistically significant.