Topographic organization of interaural intensity difference sensitivity in deep layers of cat superior colliculus: Implications of auditory spatial representation

The relationship of several data to evidence on the auditory spatial receptive fields of SC neurons is discussed, and a model of IID and azimuthal representation is proposed. IID-sensitive neurons in deep SC respond over a wide range of IIDs and will consequently be activated by stimuli at a wide range of azimuths. The model proposes that, despite broad IID and azimuthal tuning, IID (and hence auditory azimuth) could be precisely represented in terms of the relative activation of the different populations of IID-sensitive cells. This model of azimuthal coding differs from that of a receptive-field based map of space, but the topographic organization of IID sensitivity in deep SC would result in a spatial distribution of neural activity corresponding roughly to a rostral-to-caudal shift in activity as sound source azimuth shifts from frontal to lateral.