Figure 5.

Conductance records of an EI cell with ipsilaterally evoked IPSPs. This is the same cell shown in Figure 4. A, Circuit suggested by excitatory and inhibitory conductances evoked by contralateral, ipsilateral, and binaural tones shown in B and D below. B, Excitatory conductances evoked by monaural and binaural tones. The binaural excitatory conductance is smaller than the contralateral excitatory conductance, suggesting that the strength of the excitation evoked by the contralateral ear was reduced when the ipsilateral tone was introduced. C, Circuitry accounting for the excitatory conductances evoked by monaural and binaural stimulation. D, Inhibitory conductances evoked by monaural and binaural tones. In these neurons, ipsilateral tones evoked a larger inhibitory conductance than did contralateral tones. The binaural inhibitory conductance is smaller than the ipsilateral inhibitory conductance, suggesting that the strength of the inhibition evoked by the ipsilateral ear was reduced when a contralateral tone was introduced. E, Circuitry accounting for the inhibitory conductances evoked by monaural and binaural stimulation. The origin of the inhibitory projection evoked by the contralateral ear is unknown and is shown generically as coming from the cochlear nucleus; however, it most likely originates from one of the monaural nuclei of the lateral lemniscus, which are innervated by cells in the cochlear nucleus.