Comparing linear and quadratic models of the human auditory system using EEG

Recent studies have highlighted the importance of system identification as an approach for assessing sensory processing in humans using electroencephalography (EEG). These studies typically use linear impulse response estimates of visual and, more recently, auditory function. These methods, which are known as the VESPA and AESPA (Visual/Auditory Evoked Spread Spectrum Analysis) respectively, have been found to be useful for studying sensory processing in both healthy populations and clinical groups and for studying the effects of cognition on sensory processing. While a nonlinear extension of the VESPA has been previously described, no such extension has yet been examined for the AESPA. This paper investigates such an extension and quantifies the relative contribution of linear and quadratic processes to the EEG in response to novel auditory stimuli. While the ability to accurately predict novel EEG is poor, it is highly significant, with a slightly, but again significantly, greater ability to predict using a quadratic model (r=0.0418) over a linear model (r=0.0361).