Robustness of multiplicative processes in auditory spatial tuning.

Auditory space-specific neurons in the owl's inferior colliculus selectively respond to the direction of sound propagation, which is defined by combinations of interaural time (ITD) and level (ILD) differences. Mathematical analyses show that the amplitude of postsynaptic potentials in these neurons is a product of two components that vary with either ITD or ILD. Temporal correlation in the fine structure of signals between the ears is essential for detection of ITD. By varying the degree of binaural correlation, we could accurately change the amplitude of the ITD component of postsynaptic potentials in the space-specific neurons. Multiplication worked for the entire range of postsynaptic potentials created by manipulation of ITD.