Details of the whole-cell in vivo recordings are described in Supplemental Experimental Procedures. Data were acquired with GDC-0941 cost a MultiClamp 700B patch-clamp amplifier and pCLAMP 8 software (Axon Instruments). Further details are described

in Supplemental Experimental Procedures. Dual somatic whole cell and juxtacellular recordings were made at 37°C from MSO neurons in 200 μm horizontal slices prepared from P29-46 gerbils as described previously (Scott et al., 2005). Slices were bathed in ACSF containing (in mM): 125 NaCl, 25 glucose, 25 NaHCO3, 2.5 KCl, 1.25 NaH2PO4, 1.5 CaCl2, 1.5 MgSO4. Whole-cell recording electrodes were filled with (in mM): 115 K-gluconate, 4.42 KCl, 0.5 EGTA, 10 HEPES, 10 Na2Phosphocreatine, 4 MgATP, 0.3 NaGTP. Juxtacellular

recording electrodes were filled with the same solution used for in vivo juxtacellular recordings. Juxtacellular seal resistance averaged 24 ± 7 MΩ. EPSPs were evoked by local stimulation of excitatory afferents in the presence of 1 μm strychnine. IPSPs were generated via conductance clamp (Toro-8 digital signal DAPT in vivo processing board, Cambridge Conductance software) simulation of an inhibitory conductance with a double exponential waveform (time constants = 0.28 ms rise, 1.85 ms decay) and reversal potential of −85 mV. Current steps were delivered through the whole cell electrode. Data were acquired using a MultiClamp 700B amplifier and custom algorithms in IGOR Pro. EPSP data were analyzed by binning both whole cell and juxtacellular responses according to Cell press the peak EPSP amplitude measured in the whole cell recording (0.2–0.6 mV bins), then averaging the responses in each bin. Similarly, IPSP data were averaged according to the simulated conductance, and current step data were averaged according to the amplitude of the current step. Comparisons

between whole cell and juxtacellular recordings were made using these average responses. Capacitive and resistive coupling constants were estimated as described previously (Lorteije et al., 2009). Auditory stimuli were generated using custom MATLAB software. Stimuli were generated using a TDT2 system (PD1, Tucker Davis Technologies) and presented in a close-field configuration to the animal with Shure speakers (frequency range 22 Hz to 17.5 kHz) attached to the ear canal via a small tube. The correct stimulus levels and phases were attained by calibrating the drivers in situ at the level of the tympanic membrane using the microphone housed in the probe. The transfer characteristics of the probe were taken into account. All stimuli were generated at a rate of 48.8 kHz. Binaural beat stimuli consisted of a pair of pure tones, one presented to each ear. The frequencies presented to the ipsilateral ear varied between 100 Hz and 1,600 Hz in 100 Hz steps; in two experiments, the step size was reduced to 50 Hz.