Research On The Advantages Of Auditory Steady-state Responses And Its Application

Recording electrical activity from the human brain, which was based on the principle of the firing of neurons, was firstly reported by the German psychiatrist Hans Berger. Subsequently, in1960s, Sutton proposed the notion of event-related potentials, which was the responses to the external transient stimulation. Since then, the majority of studies have relied on the recording of event-related potentials, to understand the neural mechanism of human brain. More and more researchers began to use this non-invasive electroencephalographic techniques to explore the sensory neural mechanism of human brain. It has a great development of human brain researches. In addition, in1966, Regan introduced the technique of steady-state responses as an alternative approach to characterize stimulus-evoked activity in the ongoing EEG (EEG, electroencephalogaphy).Up to now, transient event-related potentials (transient ERPs) and steady-state responses (SSRs) have been popularly employed to investigate the function of the human brain, and there have been a great number of research outputs to contribute to the study of human brain. However, the relationship between transient ERPs and SSRs still remains a matter of debate. In addition, the neural mechanism of the SSRs is unclear either. Some researchers believed that SSRs could be explained by the linear summation of successive transient ERPs (superposition hypothesis), while others believed that SSRs were the result of the entrainment of a neural rhythm driven by the periodic repetition of a sensory stimulus (oscillatory entrainment hypothesis). Considering that the importance of transient event-related potentials and steady-state responses in basic and clinical studies, it is necessary to make clear of the relationship between transient ERPs and SSRs, and the neural mechanism of SSRs.In the present study, taking auditory modality as an example, the research on the advantages of auditory SSRs and its application of auditory perception in inter-subjects was performed. In the first study, we aimed to clarify the distinct features of SSRs, evoked by the40-Hz and60-Hz periodic auditory stimulation, as compared to transient ERPs, evoked by a single click. We observed that, SSRs have several advantages over the recording of transient ERPs, such as a high signal-to-noise ratio (SNR), a shorter time to obtain reliable signals, and the capacity to frequency-tag the cortical activity elicited by concurrently presented sensory stimuli. All findings indicated that, at high frequency. SSRs could reflect neural responses distinct from transient ERPs, and captured higher SNR compared to middle-latency responses and late-latency responses. Such understanding would be of great importance in both basic and clinical studies since it provided solid base for the application of SSRs, as a new window for us. to reveal novel and reliable neural mechanisms of the human brain.In the second study, we apply SSRs to study the effect that peple who have long-period musical traning, which further confirmed the advantages of SSRs. The findings show that, after long-period musical training, musicians have significantly different brain represents in different cognitive tasks by comparing to non-musicians.Such as the late-latency responses (N1and P2) in transient ERPs of musicians were significantly lower than those of nonmusicians; at low frequency (1-20Hz), phase-locking value and transient responses evoked by transient and the onset of steady-state stimuli of muscians were significantly lower than those of nonmusicians; while steady-state responses at high frequency (40-60Hz)(phase-locking value, PLV) of musicians were significantly higher than those of nonmusicians. Brain responses at low frequency represent the cognitive processing and brain responses at high freauency represent the processing of perception. The long-period musical training may cause the reconstructrue in huaman brain, and enhance the ability of processing of auditory stimulation and the ability of cognitive control. Long-term musical training could enhance the auditory information processing in the sensory system, which may be caused by training-induced neuroplasticity. In addition, the "top-down" cognitive inhibition to the novelty/saliency detection system has been enhanced, which indicated that, musicians could focus more attention to their own world by suppressing interference.In conclusion, the present study explored the distinct features between transient ERPs and SSRs and summarized the advantages of SSRs, which would make more contributes to further study of neural mechenism. According to the study of the difference between musicians and non-musicians, providing evidences to basic and clinical research, which contribute to the development of study of human brain.