Figure 6.
Example of a low-characteristic-frequency LSO neuron that is sensitive to ILDs and IPDs. A, Frequency-threshold curve (characteristic frequency, 566 Hz). B-D, The same as in Figure 5. ϕ, Mean interaural phase;ϕb, mean interaural phase from binaural-beat stimuli; *p < 0.001. E, Noise-delay function created by plotting the mean discharge rate as a function of the ITD of a broadband noise presented to the two ears with equal amplitude. Negative delays indicate that the contralateral stimulus lags the ipsilateral stimulus. Consistent with the CD (235 μs) and the CP (0.47 cycles) obtained from the binaural-beat stimulus for this neuron (C, D), the response minimum in the noise-delay function occurs at an ipsilateral delay of 200 μs, which is near the delay of 235 μs predicted from the CD. At the CD, the ipsilateral excitation and the contralateral inhibition arrive coincidentally at the LSO neuron, resulting in maximal inhibition. Error bars in B and E represent ±1 SEM. SPL, Sound pressure level; IPSI or Ipsi, ipsilateral; CONTRA or Contra, contralateral.