Figure 4.

A, An EI cell in which a contralateral tone evoked a suprathreshold EPSP and ipsilateral signals only evoked IPSPs that increased with intensity. With binaural signals, the contralaterally evoked spikes were progressively suppressed as ipsilateral sound intensity was increased. The spike suppression mirrored the increases in IPSP amplitudes with ipsilateral intensity, suggesting that the EI property was created de novo in the IC with the circuitry shown in Figure 1B. B, Excitatory response to a 10 dB SPL contralateral tone aligned with IPSPs evoked by ipsilateral tones at different intensities, showing that the latencies of the IPSPs were coincident with the EPSP evoked by a contralateral tone. C, IID function of spike counts. Tone duration, 5.0 ms.