Research On The Dynamic Process Of Brain Responses Modulated By The Perceptual Timing Template

Expectations are brain states that reflect prior information about what is possible or probable in the forthcoming sensory environment. Because of the behavioural effects of expectations and attention are superficially identical, the neural effects of expectations often tend to be mixed with those of attention. Recent studies have found that expectations are specific responses that different from attention and have explored the neural sources of expectations and the interactions between them. However, the dynamic process of brain responses in the expectations remains unknown. Predictive coding proposes that our brains will generate a template to match with the incoming stimulation during the process of expectations. When stimulation conforms to expectations, matching response will happen. When sensory evidence diverges from expectations, error response will happen. Then the difference between the electrophysiological mechanism of matching response and error response become the key problems in revealing the dynamic process of brain responses in the expectations.A temporal expectations experiment based on visual stimulation was designed. and the EEG data of 14 healthy subjects were collected. The waveforms of the EEG data in the time domain, the inter-trial coherence in time-frequency domain and brain network based on PDC(Partial Directed Coherence) were got. The behavioral data were also analyzed in the two tasks. The results of the behavioral data show that the response time of the subjects in the match trials is shorter than that in the non-match trials prominently, indicating that the correct expectations speed up the reaction of the subjects. The results of the waveforms in the time domain show that the visual N1 peaks earlier over frontal than posterior regions of the scalp, suggestive of distinct neural and/or cognitive correlates. Topographies show that the scalp distribution of the mean amplitude of the visual N1 is larger in the match trials than in the non-match trials over the entire scalp. This indicates that the degree of brain activation in two kinds of response have differences. The results of the brain network based on PDC show that the clustering coefficient of the network in the matching response of ?, ?, ? and ? frequency bands is higher than that in the error response, indicating that the networks of these frequency bands are more complex than that in the error response and the operation efficiency in the matching response is higher. The betweenness centrality of the network in the matching response of ?, ? and ? frequency bands show that the bottom-up influence is higher in the process of error response and top-down influence is higher in the process of matching response.The results of phase synchronization in the time-frequency domain show that the enhanced effect of phase synchronization caused by matching response is at the same time at certain areas of parietal-temporal-occipital association cortex and at certain areas of the right frontal cortex. The enhanced effect of phase synchronization caused by error response was prior at certain areas of parietal-temporal-occipital association cortex compared to certain areas of the right frontal cortex. The results show that the information transmission in the two response have differences: information in the matching response transfers almost at the same time, and the information in the error response transfers from the primary to higher cortical cortex step by step.The results of this study will provide theoretical and technical support for the further study of neural mechanisms and the process of information transmission in the temporal expectations.