The scalp-recorded auditory steady-state response (ASSR) is a periodically evoked potential in response to the stimulation with the acoustical property in the same period. The ASSR can be readily induced in comparison with transient responses for specific conditions. The clinical utility of ASSR may be unjustified for the ambiguity of the genesis. With the advance of relevant research, it is considered that the main generation hypotheses of the ASSR are conceived to be pertinent with the linear superposition or neural entrainment mechanism. Based on current findings and our contributions in this field, we introduce recent progresses of the two mechanisms with comments, and suggest the benefit of the rapid stimulation technology in this regard.
The maximum length sequence (m-sequence) has been successfully used to study the linear/nonlinear components of auditory evoked potential (AEP) with rapid stimulation. However, more study is needed to evaluate the effect of the m-sequence order in terms of the noise attenuation performance. This study aimed to address this issue using response-free electroencephalogram (EEG) and EEGs with nonlinear AEPs. We examined the noise attenuation ratios to evaluate the noise variation for the calculations of superimposed averaging and cross-correlation, respectively, which constitutes the main process in the deconvolution method using the dataset of spontaneous EEGs to simulate the cases of different orders (order 5 to 12) of m-sequences. And an experiment using m-sequences of order 7 and 9 was performed in true cases with substantial linear and nonlinear AEPs. The results demonstrate that the noise attenuation ratio is well agreed with the theoretical value derived from the properties of m-sequences on the random noise condition. The comparison of waveforms for AEP components from two m-sequences showed high similarity suggesting the insensitivity of AEP to the m-sequence order. This study provides a more comprehensive solution to the selection of m-sequences which will facilitate the feasible application on the nonlinear AEP with m-sequence method.