Analysis of Sensory Coding in the Lateral Superior Olive

The fundamental questions of sensory neuroscience are how neurons encode information and how neurons extract (process) information. For example, in the auditory system, sound location is determined by a combination of amplitude and time cues. The Lateral Superior Olive (LSO), one of the first nuclei to receive inputs from both ears, is thought to extract high-frequency localization information based on interaural level difference (ILD) and interaural time difference (ITD) cues. However, while the optimal localization processing system produces the same response for the same ILD regardless of source level,1 LSO responses are affected by source level. This sensitivity questions the presumption that the LSO is strictly an angle processor, and suggests that the LSO may be coding other stimulus features such as sound level. We have used a new analysis technique to analyze the significance of the LSO sensitivity to sound level compared to that of an optimal angle processor. We also examined the processing of two features: azimuthal angle and source level by the LSO network by comparing the response sensitivity of network inputs with that of its outputs.