The sound localization of barn owl with respect to horizontal and vertical direction is made based on analysis of the interaural differences in arrival time and intensity of sound, respectively. The neural information processing of detection of interaural intensity difference (IID) is made on the neural pathway parallel with the pathway of interaural time difference (ITD) detection before both the signals arrive at the shell of central nucleus of the inferior colhculus (ICc shell). We have presented a neural model of ITD detection pathway (Inoue et al, Neurocomputing 2001, vol.38-40,pp.675-682). In the present paper, we present a neuronal model of the nucleus ventralis lemnisci lateralis pars posterior (VLVp) in which the signals of sound intensities coming from both the ears are first combined to be compared with each other. We clarify the functional role of mutual inhibitory connections between both VLVps observed' experimentally in detection of IID. Outputs of IID sensitive neurons in both VLVps are projected bilaterally to ICc shell and the connections are inhibitory, whereas outputs of ITD sensitive neurons in ICc core projected to ICc shell are excitatory.It is shown using our neuronal models of VLVps, ICc core, and ICc shell that the neural map, in which ITD and IW are represented along the axes perpendicular mutually, can be generated in ICc shell by the excitatory inputs from ICc core and the inhibitory inputs from bilateral VLVps, as observed experimentally.Then, the mutually inhibitory coupling between both VLVps controls the spatial firing patterns of arrays of IID sensitive neurons in both VLVps so that the neurons only at the site corresponding to the relevant value of IID in the map can fire.
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