THE CROSS-MODAL STUDY ON ERP DEVIANCE-RELATED COMPONENTS OF CHINESE LANGUAGE
1997, 29 (04):
Even-related potentials (ERPs) were measured in 15 normal young subjects using the paradigm "Cross-modal and delayed response" proposed by Wei Jinghan, which was able to improve inattention purity and to avoid the effect of task target on the deviance-related components (DRC) of ERPs. The experiment was conducted under two conditions: one is attending to the visual modality but ignoring the auditory modality, the other is attending to the auditory modality but ignoring the visual modality. A series of five kinds of stimuli were presented to every subject: standard, deviant stimuli and response imperative signal in attended channel; standard and deviant stimuli in unattended channel. The visual and auditory stimuli presented in a pseudo-random order with a probability of standard stimuli was 82.5% and deviant stimuli was 17.5%. Every standard or deviant stimulus was followed by a response imperative signal in attended channel. The DRC was obtained by subtracting the ERPs of the standard stimuli from that of the deviant stimuli. The present results showed: ① The largest N1 peak elicited by spoken words was located at the fronto-cental scalp and the N1 elicited by the written words was located at lateral occipital and posteriortemporal area regardless of modality or attention condition. This showed an obvious modality difference and suggested that the N1 elicited by verbal is probably specific index reflecting primary processing of Chinese shape and sound. ② Under both attended and strict unattended conditions, an early deviance-related negativity (DRN1) was evoked by using Chinese orthographic and phonological processing. The basic properties, such as peak latency, distribution and attention effects were analogous with the mismatch negativity (MMN) except for scalp distrbution of DRN1 peak evoked under the unattended condition. In addition, these properties of DRN1 yielded by visual verbal and non-verbal stimuli were also proved the same as auditory MMN Regarding the question as to whether or not visual MMN and verbal MMN existed, it can be initially believed that the MMN existed in the visual modality and in the language processing process in the current experiment ③ According to the characteristics of N350 peak latencies, amplitudes and its scalp distribution, the current results suggested that the N350 is overlapping of N200 and N400, but N400 played a more important role under the attended condition. On the other hand, the N350 consisted mainly of the N200 component under the unattended condition. They were not immutable and this gives an expression that ERPs components reflect a plasticity of the processing mechanism in the brain.
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